{"id":75,"date":"2019-03-07T09:36:54","date_gmt":"2019-03-07T09:36:54","guid":{"rendered":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/chapter\/__unknown__\/"},"modified":"2020-05-12T14:47:33","modified_gmt":"2020-05-12T13:47:33","slug":"__unknown__","status":"publish","type":"chapter","link":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/chapter\/__unknown__\/","title":{"raw":"SHORT CIRCUIT CALCULATIONS \u2013 EXERCISE","rendered":"SHORT CIRCUIT CALCULATIONS \u2013 EXERCISE"},"content":{"raw":"<div class=\"__UNKNOWN__\">\r\n<p class=\"import-Normal\" style=\"text-align: center\"><span xml:lang=\"en-US\" lang=\"en-US\">SHORT CIRCUIT CALCULATIONS \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">EXERCISE<\/span><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: center\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image1.png\" alt=\"image\" width=\"604.8px\" height=\"342.322099737533px\" \/><\/p>\r\n<a id=\"_Toc2847051\"><\/a><strong>Aim of the excercise<\/strong>\r\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The main purpose of the exercise is to familiarize students with the model example of short circuit calculations. It is proposed to perform the exercise on the basis of the actual power system. Short-circuit calculations are the basis for the selection of electrical apparatus and devices.<\/span><\/p>\r\n<strong>Basic information<\/strong>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">Short-circuit is defined as a disturbance consisting in the connection of power network points with different potentials, resulting from the loss of insulating properties of its elements. It is accidental or intentional conductive path between two or more conductive parts forcing the electric potential differences between these conductive parts to be equal or close to zero.<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">Electrical installations nearly always require protection against short-circuits. The short-circuit current have to be calculated at each level in the installation for determining the characteristic parameters of the equipment required to withstand or break the fault current.<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">Calculation of normal operation conditions and short circuit calculations are made on the basis of electrical standards:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60050 International Electrotechnical Vocabulary (IEV)<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60909-0:2016 Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60865-1:2011 Short-circuit currents - Calculation of effects - Part 1: Definitions and calculation methods<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEEE Std 551-2006 IEEE Recommended Practice for Calculating Short-Circuit Currents in Industrial and Commercial Power Systems<\/li>\r\n<\/ul>\r\n<p class=\"import-Nagwek1\"><strong><a id=\"_Toc2847053\"><\/a><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The rules for calculating the characteristic parameters of normal operation<\/span><\/strong><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The basic parameters for normal operation for the calculation of the selection of electrical apparatus and devices are shown in Table 1.<\/span><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Table 1. The basic parameters for normal operation for the calculation of the selection of electrical apparatus and devices<\/span><\/p>\r\n\r\n<table>\r\n<tbody>\r\n<tr class=\"Tabela-Siatka-R\" style=\"height: 22.5pt\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Characteristic<\/strong> <strong>parameter<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\" colspan=\"2\">\r\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Equation<\/strong><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Nominal (rated) voltage<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: none windowtext 0pt;border-left: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><span style=\"font-size: 14pt;color: #;text-decoration: none\">Un\u2265U<sub>n_grid<\/sub><\/span><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: solid windowtext 0.5pt;border-left: none windowtext 0pt\">\r\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">Un <\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">rated voltage of a device<\/span><\/div>\r\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">Un_grid <\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">rated voltage of a grid, where the device is placed<\/span><\/div><\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\" style=\"height: 62.7pt\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Nominal (rated) current<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: none windowtext 0pt;border-left: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><span style=\"font-size: 14pt;color: #;text-decoration: none\">I<sub>n<\/sub>&gt;I<sub>load<\/sub><\/span><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: solid windowtext 0.5pt;border-left: none windowtext 0pt\">\r\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">In<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">rated current<\/span><\/div>\r\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">Iload<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">load current<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> based on the power of supplied device<\/span><\/div><\/td>\r\n<\/tr>\r\n<tr>\r\n<td><\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p class=\"import-Normal\">The main procedure for calculating short circuit parameters for LV installation is shown on Fig. 1.<\/p>\r\n<p class=\"import-Normal\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image2.png\" alt=\"image\" width=\"604.8px\" height=\"411.533333333333px\" \/><\/p>\r\n<p class=\"import-Normal\">Fig. 1. Short-circuit (<em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>sc<\/em><\/sub>) calculation procedure for low-voltage electrical installation (ST - short time; Inst. - instantaneous)[5]<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">The main characteristics of short-circuits are:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Duration (self-extinguishing, transient and steady-state)<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Origin: mechanical (break in a conductor, accidental electrical contact between two conductors via a foreign conducting body such as a tool or an animal), internal (switching) or atmospheric overvoltages, insulation breakdown due to heat, humidity or a corrosive environment<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Location<\/li>\r\n<\/ul>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">There can be different types of a short-circuit: phase-to-eartch (80% of faults), phase-to-phase (15% of faults), three-phase (5% of faults).<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">Electrical devices should withstand both thermal and electrodynamic short-circuit currents. In addition, apparatusses used to connect short-circuit currents should have sufficient connectivity. The proper selection of electrical equipment is based on the appropriate selection of short-circuit parameters of the power system in the place where the device is installed. The calculation of short-circuit parameters is performed for the most difficult possible short-circuit cases, i.e. for a three-phase fault directly on the circuit breaker's terminals. The basic short-circuit parameters of electrical apparatus include:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Peak withstand current <em>i<\/em><sub>pwc<\/sub><\/li>\r\n<\/ul>\r\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">i<sub>pwc<\/sub>\u2265i<sub>surge\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/sub><\/span>(1)<\/div>\r\n<p class=\"import-Normal\" style=\"margin-left: 35.45pt\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">i<sub>surge <\/sub><\/span>\u2013 surge current<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Short time withstand current <em>I<\/em><sub>k<\/sub><\/li>\r\n<\/ul>\r\n<p id=\"poWtGTg\"><img class=\"alignnone size-full wp-image-80 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935a99a80e5.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (2)<\/p>\r\n<p class=\"import-Normal\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>tz\u00a0<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">equivalent short- circuit <\/span><em lang=\"en-US\" xml:lang=\"en-US\">t<\/em><sub><em>z<\/em><\/sub><span xml:lang=\"en-US\" lang=\"en-US\">-se<\/span><span xml:lang=\"en-US\" lang=\"en-US\">conds current<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">t<sub>z<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">time of short-circuit<\/span><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">The above inequality applies for cases where t<sub>z<\/sub>\u2265n<span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">If <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">t<sub>z<\/sub>&lt;n<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><span xml:lang=\"en-US\" lang=\"en-US\">then the apparatus or a device should be selected like for <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">t<sub>z<\/sub>=n <\/span><span xml:lang=\"en-US\" lang=\"en-US\">or its selection should be made according to the manufacturer<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">The duration of the short-circuit is determined by the circuit breaker nearest to the fault location<\/span><span xml:lang=\"en-US\" lang=\"en-US\">.<\/span><\/p>\r\n<p class=\"import-Normal\"><strong>CALCULATIONS OF SHORT-CIRCUIT CURRENTS<\/strong><\/p>\r\n<p class=\"import-Normal\">a) Initial short-circuit current <span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>peak<\/sub><\/span><\/p>\r\n<p id=\"Ucvogoi\"><img class=\"alignnone wp-image-81 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935b9a1755a.png\" alt=\"\" width=\"217\" height=\"52\" \/> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 (3)<\/p>\r\n<p class=\"import-Normal\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">U<sub>n <\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">nominal (rated) voltage of a grid<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><em lang=\"en-US\" xml:lang=\"en-US\">k<\/em> \u2013 factor depending on the load of a system; for typical cases it is assumed as <em lang=\"en-US\" xml:lang=\"en-US\">k<\/em> = 1,1, <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> \u2013 <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">factor depending on the type of fault; for a three-phase fault<\/span> <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> = 1<\/p>\r\n<p class=\"import-Normal\">b) Surge current <em>I<sub>surge<\/sub><\/em><\/p>\r\n\r\n<div>\r\n\r\n<img class=\"alignnone wp-image-82 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935bb634fcb.png\" alt=\"\" width=\"205\" height=\"33\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (4)\r\n\r\n<\/div>\r\n<p class=\"import-Normal\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">k<sub>u<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">coefficient determined from Fig. 2<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>peak<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">initial short-circuit current<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> \u2013 <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">factor depending on the type of fault; for a three-phase fault<\/span> <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> = 1<\/p>\r\n<p class=\"import-Normal\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image4.png\" alt=\"image\" width=\"604.8px\" height=\"278.030551181102px\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: center\">Fig 2. Dependence of an coefficient <em lang=\"en-US\" xml:lang=\"en-US\">k<\/em><sub><em>u<\/em><\/sub> from the quotient <em lang=\"en-US\" xml:lang=\"en-US\">R<\/em> and <em lang=\"en-US\" xml:lang=\"en-US\">X<\/em><\/p>\r\nc) Rated short-time withstand current <em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>th1s<\/em><\/sub>\r\n<p id=\"OpTpIJE\"><img class=\"alignnone wp-image-83 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935bed919d1.png\" alt=\"\" width=\"147\" height=\"39\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (5)<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">k<sub>c <\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\">\u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">coefficient taking into account the disappearance of the periodic current component during short circuit determined from Fig. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">3, <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>peak<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">initial short-circuit current<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> \u2013 factor depending on the type of fault; for a three-phase fault <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> = 1<\/p>\r\n<p id=\"quvibHj\"><img class=\" wp-image-85 aligncenter\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935ca77eed5.png\" alt=\"\" width=\"474\" height=\"595\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: center\">Fig. 3. Dependence of the coefficient <em lang=\"en-US\" xml:lang=\"en-US\">k<\/em><sub><em>c<\/em><\/sub> from quotient <em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>1<\/em><\/sub> and <em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>n<\/em><\/sub> and the time of short-circuit <em lang=\"en-US\" xml:lang=\"en-US\">t<\/em><sub><em>z<\/em><\/sub> [PN-E-05002:1974]<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify;text-indent: 42.55pt\">Coefficient k<sub>c<\/sub> is determined from Fig. 3 <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">and depends on the duration of the fault and the ratio of the component of the <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">initial short-circuit<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> current and the sum of currents from all sources that can <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">supply<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> the short circuit. In the case of fault duration with a value other than those specified in Fig. 3, linear interpolation should be used.<\/span><\/p>\r\n<p class=\"import-Nagwek2\"><a id=\"_Toc2847054\"><\/a><strong>Calculations for selection of current transformers<\/strong><\/p>\r\na) Current of primary side of current transformer\r\n<p id=\"CwcTbVw\"><img class=\"alignnone wp-image-86 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935dad629c8.png\" alt=\"\" width=\"144\" height=\"50\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <span xml:lang=\"en-US\" lang=\"en-US\">(6)<\/span><\/p>\r\nb) Load power\r\n<p id=\"KCSwskq\"><img class=\"alignnone wp-image-87 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935dcfe9da0.png\" alt=\"\" width=\"315\" height=\"39\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 \u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (7)<\/p>\r\n<p class=\"import-Normal\">gdzie: <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>cables<\/em><\/sub> \u2013 power of losses from cables, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>measurement<\/em><\/sub> \u2013 power of losses from measurement device, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>contacts<\/em><\/sub> \u2013 power of losses from contacts<\/p>\r\n<p class=\"import-Normal\">It can be assumed that:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Normal\">Power losses on measurement device are 0,01 VA<\/li>\r\n \t<li class=\"import-Normal\">Power losses on contacts are 1,25 VA<\/li>\r\n \t<li class=\"import-Normal\">Power losses on cables need to be calculated from (8)<\/li>\r\n<\/ul>\r\n<div>\r\n\r\n<img class=\"alignnone size-full wp-image-88 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935e6f46c83.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (8)\r\n\r\n<\/div>\r\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The correct choice of parameters consists in checking inequalities<\/span> <span xml:lang=\"en-US\" lang=\"en-US\">(9) <\/span><span xml:lang=\"en-US\" lang=\"en-US\">and<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> (10).<\/span><\/p>\r\n\r\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">0,25\u2219S<sub>N<\/sub>\u2264S<sub>obl<\/sub>\u2264S<sub>N<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">(9)<\/span><\/div>\r\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">0,6\u2219I<sub>Np<\/sub>\u2264I<sub>obl<\/sub>\u22641,2\u2219I<sub>Np<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">(10)<\/span><\/div>\r\n<p class=\"import-Nagwek2\"><strong><a id=\"_Toc2847055\"><\/a><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Selection of voltage measuring transformers in MV networks<\/span><\/strong><\/p>\r\na) Voltage of primary side\r\n<div>\r\n\r\n<img class=\"alignnone wp-image-89 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935eb6bf9e1.png\" alt=\"\" width=\"103\" height=\"43\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (11)\r\n\r\n<\/div>\r\nb) Rated isolation level\r\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Due to the nominal primary voltage of the transformer, <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">eg<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> in MV networks, the rated is<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">o<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">lation level should be selected as<\/span> 17,5\/38\/95, where:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">17,5 kV \u2013 highest possible voltage (RMS)<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">38 kV \u2013 rated short-time test voltage on network frequency (RMS)<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">95 kV \u2013 rated test lighting voltage (max value))<\/li>\r\n<\/ul>\r\n<span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">c) Rated secondary voltage of the measuring transformer depending on the connection system<\/span>\r\n<div>\r\n\r\n<img class=\"alignnone size-full wp-image-90 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935f1c2b5dc.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (12)\r\n\r\n<\/div>\r\nd) Load power\r\n\r\n<img class=\"alignnone wp-image-87 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935dcfe9da0.png\" alt=\"\" width=\"315\" height=\"39\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (13)\r\n<p class=\"import-Normal\">gdzie: <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>cables<\/em><\/sub> \u2013 power of losses from cables, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>measurement<\/em><\/sub> \u2013 power of losses from measurement device, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>contacts<\/em><\/sub> \u2013 power of losses from contacts<\/p>\r\n<p class=\"import-Normal\">It can be assumed that:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Normal\">Power losses on measurement device are 0,01 VA<\/li>\r\n \t<li class=\"import-Normal\">Power losses on contacts are 1,25 VA<\/li>\r\n \t<li class=\"import-Normal\">Power losses on cables need to be calculated from (8)<\/li>\r\n<\/ul>\r\n<p class=\"import-Nagwek2\"><strong><a id=\"_Toc2847056\"><\/a><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> calculation<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> task of choosing electrical devices<\/span><\/strong><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\">On the <\/span><span class=\"import-tlid-translation\">basis<\/span><span class=\"import-tlid-translation\"> of Fig. <\/span><span class=\"import-tlid-translation\">4<\/span><span class=\"import-tlid-translation\">, <\/span><span class=\"import-tlid-translation\">appropriate<\/span> <span class=\"import-tlid-translation\">electrical<\/span> <span class=\"import-tlid-translation\">equipment<\/span> <span class=\"import-tlid-translation\">should<\/span><span class=\"import-tlid-translation\"> be <\/span><span class=\"import-tlid-translation\">selected<\/span><span class=\"import-tlid-translation\">. The system <\/span><span class=\"import-tlid-translation\">is<\/span> <span class=\"import-tlid-translation\">powered<\/span><span class=\"import-tlid-translation\"> from MV network with GPZ with 3x <\/span><span class=\"import-tlid-translation\">XRUHAKXs<\/span><span class=\"import-tlid-translation\"> 1x240 mm2 cables. The MV <\/span><span class=\"import-tlid-translation\">switchgear<\/span> <span class=\"import-tlid-translation\">is<\/span> <span class=\"import-tlid-translation\">constructed<\/span><span class=\"import-tlid-translation\"> from <\/span><span class=\"import-tlid-translation\">two<\/span> <span class=\"import-tlid-translation\">sections<\/span><span class=\"import-tlid-translation\">; from <\/span><span class=\"import-tlid-translation\">each<\/span> <span class=\"import-tlid-translation\">section<\/span><span class=\"import-tlid-translation\">, 4 <\/span><span class=\"import-tlid-translation\">dry<\/span> <span class=\"import-tlid-translation\">transformers<\/span><span class=\"import-tlid-translation\"> 15 \/ 0.4 <\/span><span class=\"import-tlid-translation\">kV<\/span> <span class=\"import-tlid-translation\">are<\/span> <span class=\"import-tlid-translation\">supplied<\/span> <span class=\"import-tlid-translation\">through<\/span><span class=\"import-tlid-translation\"> MV <\/span><span class=\"import-tlid-translation\">circuit<\/span> <span class=\"import-tlid-translation\">breakers<\/span><span class=\"import-tlid-translation\"> and 3x <\/span><span class=\"import-tlid-translation\">XRUHAKXs<\/span><span class=\"import-tlid-translation\"> 1 x 120 mm2 <\/span><span class=\"import-tlid-translation\">cable<\/span><span class=\"import-tlid-translation\"> lines. <\/span><span class=\"import-tlid-translation\">From<\/span> <span class=\"import-tlid-translation\">transformers<\/span> <span class=\"import-tlid-translation\">are<\/span> <span class=\"import-tlid-translation\">powered<\/span> <span class=\"import-tlid-translation\">low<\/span> <span class=\"import-tlid-translation\">voltage<\/span> <span class=\"import-tlid-translation\">switchgears<\/span><span class=\"import-tlid-translation\"> via LV <\/span><span class=\"import-tlid-translation\">switches<\/span>.<\/p>\r\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\">For the <\/span><span class=\"import-tlid-translation\">short-circuit<\/span> <span class=\"import-tlid-translation\">loop<\/span> <span class=\"import-tlid-translation\">impedance<\/span> <span class=\"import-tlid-translation\">calculation<\/span><span class=\"import-tlid-translation\">, <\/span><span class=\"import-tlid-translation\">use<\/span><span class=\"import-tlid-translation\"> the <\/span><span class=\"import-tlid-translation\">following<\/span> <span class=\"import-tlid-translation\">relationships<\/span>:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">For cables<\/li>\r\n<\/ul>\r\n<p id=\"bgrtbQQ\"><img class=\"alignnone wp-image-91 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c9360294a69e.png\" alt=\"\" width=\"74\" height=\"54\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 (14)<\/p>\r\n<p class=\"import-Normal\">where: - unit cable resistance, - reaktancja jednostkowa linii kablowej<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">for two-windings (MV\/LV) transformers<\/li>\r\n<\/ul>\r\n<p id=\"jRwnBPF\"><img class=\"alignnone wp-image-93 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c93605775223.png\" alt=\"\" width=\"138\" height=\"111\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (15)<\/p>\r\n<p class=\"import-Normal\">where:\u00a0\u0394U<sub>zw%<\/sub> - impedance voltage at rated current, \u0394P<sub>R(kW)<\/sub>- <span class=\"import-tlid-translation\">rated<\/span> <span class=\"import-tlid-translation\">load<\/span> <span class=\"import-tlid-translation\">power<\/span> <span class=\"import-tlid-translation\">losses<\/span><\/p>\r\n<p class=\"import-Normal\"><strong>ATTENTION!!<\/strong><\/p>\r\n<p class=\"import-Normal\">When setting an impedance substitute circuit, it is important to remember that the impedance of individual elements must relate to one voltage level!<\/p>\r\n<p id=\"oJVubsa\"><img class=\"alignnone size-full wp-image-96 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c9360e4c567c.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (16)<\/p>\r\n<p class=\"import-Normal\" style=\"text-align: center\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image16.png\" alt=\"image\" width=\"811.777952755906px\" height=\"573.6px\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: center\"><span xml:lang=\"en-US\" lang=\"en-US\">Fig<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">4<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Diagram of the power supply system for the task of choosing electrical devices<\/span><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\">The data for the <\/span><span class=\"import-tlid-translation\">task<\/span> <span class=\"import-tlid-translation\">is<\/span><span class=\"import-tlid-translation\"> set out in <\/span><span class=\"import-tlid-translation\">Tables<\/span><span class=\"import-tlid-translation\"> 2-5. The <\/span><span class=\"import-tlid-translation\">duration<\/span><span class=\"import-tlid-translation\"> of the <\/span><span class=\"import-tlid-translation\">short<\/span> <span class=\"import-tlid-translation\">circuit<\/span><span class=\"import-tlid-translation\"> in the <\/span><span class=\"import-tlid-translation\">low<\/span> <span class=\"import-tlid-translation\">voltage<\/span><span class=\"import-tlid-translation\"> network <\/span><span class=\"import-tlid-translation\">should<\/span><span class=\"import-tlid-translation\"> be <\/span><span class=\"import-tlid-translation\">taken<\/span> <span class=\"import-tlid-translation\">at<\/span><span class=\"import-tlid-translation\"> 0.4 s<\/span>.<\/p>\r\n<p class=\"import-Normal\"><span xml:lang=\"en-US\" lang=\"en-US\">Tab<\/span><span xml:lang=\"en-US\" lang=\"en-US\">le<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> 2. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Basic data for the <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">calculation <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">task<\/span><\/p>\r\n\r\n<table style=\"width: 616px\">\r\n<tbody>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\"><strong>Team No<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\"><strong lang=\"en-US\" xml:lang=\"en-US\">Power of a system<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> [MVA]<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\"><strong>Indicated<\/strong><strong> transformer<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\"><strong lang=\"en-US\" xml:lang=\"en-US\">Short-circuit time in MV grid<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> [s]<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\"><strong class=\"import-tlid-translation\" lang=\"en-US\" xml:lang=\"en-US\">Short circuit power<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> of a system<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\">\u2013 <\/strong><strong lang=\"en-US\" xml:lang=\"en-US\">multiplier<\/strong><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">50<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,6<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">2<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">60<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">3<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">80<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">4<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">90<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,0<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">1,5<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">5<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">120<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">0,8<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">2,5<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">6<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">85<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">0,9<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">7<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">7<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">75<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">0,7<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">5<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">8<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">55<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">0,5<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">10<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">9<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">65<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,0<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">3,5<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">10<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">45<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,5<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">5<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">11<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">90<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">6<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\r\n<p class=\"import-Normal\">12<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\r\n<p class=\"import-Normal\">110<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\r\n<p class=\"import-Normal\">1,1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\r\n<p class=\"import-Normal\">5,5<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td style=\"width: 54.9667px\"><\/td>\r\n<td style=\"width: 129.367px\"><\/td>\r\n<td style=\"width: 125.8px\"><\/td>\r\n<td style=\"width: 108.433px\"><\/td>\r\n<td style=\"width: 141.433px\"><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p class=\"import-Normal\"><span xml:lang=\"en-US\" lang=\"en-US\">Tab<\/span><span xml:lang=\"en-US\" lang=\"en-US\">le<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> 3. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">Rated parameters of transformers<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> 15\/0,4 kV<\/span><\/p>\r\n\r\n<table>\r\n<tbody>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>Indicated<\/strong><strong> transformer<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>Nominal<\/strong><strong> (<\/strong><strong>rated<\/strong><strong>) <\/strong><strong>power<\/strong><strong> [<\/strong><strong>kVA<\/strong><strong>]<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>I<\/strong><strong>mpedance<\/strong> <strong>voltage<\/strong> <strong>at<\/strong> <strong>rated<\/strong> <strong>current<\/strong> <strong>[%]<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>Rated<\/strong> <strong>load<\/strong> <strong>power<\/strong> <strong>losses<\/strong><strong> [W]<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong class=\"import-tlid-translation\">The <\/strong><strong class=\"import-tlid-translation\">length<\/strong><strong class=\"import-tlid-translation\"> of the <\/strong><strong class=\"import-tlid-translation\">cable<\/strong> <strong class=\"import-tlid-translation\">line<\/strong> <strong class=\"import-tlid-translation\">powering<\/strong><strong class=\"import-tlid-translation\"> the <\/strong><strong class=\"import-tlid-translation\">device<\/strong> <strong>[m]<\/strong><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">2000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">16000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1000<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1600<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">6<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">13000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">800<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">8<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">9000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">850<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 1 \u2013 trafo 4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">3150<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">10<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">22000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">700<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">3150<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">22000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1100<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">6<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">9000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">560<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1600<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">8<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">13000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">485<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">Section 2 \u2013 trafo 4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">2000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">10<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">16000<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1050<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p class=\"import-Normal\">Table 4. <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Additional parameters to complete the task<\/span><\/p>\r\n\r\n<table>\r\n<tbody>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>No in team<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong lang=\"el-GR\" xml:lang=\"el-GR\">\u03c8<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong lang=\"en-US\" xml:lang=\"en-US\">Length of a cable<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> L1 [m]<\/strong><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">3,5<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">200<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">2<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">3,3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">250<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">3<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">3,1<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">150<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">4<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">2,8<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">320<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p class=\"import-Normal\">Table 5. <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The rated parameters of cable lines<\/span><\/p>\r\n\r\n<table>\r\n<tbody>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>Cable<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>Unit <\/strong><strong>resistance<\/strong><strong> [<\/strong><strong>\u2126<\/strong><strong>\/km]<\/strong><\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\"><strong>Unit reactance<\/strong><strong> [<\/strong><strong>\u2126<\/strong><strong>\/km]<\/strong><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">XRUHAKXs 1x240<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">0,125<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">0,58<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr class=\"Tabela-Siatka-R\">\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">XRUHAKXs 1x120<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">0,253<\/p>\r\n<\/td>\r\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\r\n<p class=\"import-Normal\">0,182<\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><\/td>\r\n<td><\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p class=\"import-Nagwek2\"><strong><a id=\"_Toc2847057\"><\/a><span class=\"import-tlid-translation\">Short-circuit<\/span> <span class=\"import-tlid-translation\">current<\/span> <span class=\"import-tlid-translation\">course<\/span><\/strong><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">You can use the MATLAB software and the script below to plot the short-circuit current. The output data is: the effective value of the short-circuit current in kA, the phase of current switching <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">in<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> rad, the short-circuit time in s<\/span>.<\/p>\r\n<p class=\"import-Normal\">MATLAB programme<\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-GB\" xml:lang=\"en-GB\">clear all;<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-GB\" xml:lang=\"en-GB\">close all;<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>clc<\/em><em>;<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>format compact;<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-US\" xml:lang=\"en-US\">disp<\/em><em lang=\"en-US\" xml:lang=\"en-US\">('<\/em><em lang=\"en-US\" xml:lang=\"en-US\">T<\/em><em lang=\"en-US\" xml:lang=\"en-US\">he effective value of the short-circuit current <\/em><em lang=\"en-US\" xml:lang=\"en-US\">[kA]');<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>I = <\/em><em>input<\/em><em>('I = ');<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-US\" xml:lang=\"en-US\">disp<\/em><em lang=\"en-US\" xml:lang=\"en-US\">('<\/em><em lang=\"en-US\" xml:lang=\"en-US\">Phase of current <\/em><em lang=\"en-US\" xml:lang=\"en-US\">switching<\/em><em lang=\"en-US\" xml:lang=\"en-US\">w<\/em><em lang=\"en-US\" xml:lang=\"en-US\"> [rad]');<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>psi = <\/em><em>input<\/em><em>('psi = ');<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-US\" xml:lang=\"en-US\">disp<\/em><em lang=\"en-US\" xml:lang=\"en-US\">('<\/em><em lang=\"en-US\" xml:lang=\"en-US\">Short-circuit <\/em><em lang=\"en-US\" xml:lang=\"en-US\">time<\/em><em lang=\"en-US\" xml:lang=\"en-US\">w<\/em><em lang=\"en-US\" xml:lang=\"en-US\"> [s]');<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>tz<\/em><em> = <\/em><em>input<\/em><em>('<\/em><em>tz<\/em><em> = ');<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>Im = I*<\/em><em>sqrt<\/em><em>(2)*1e3;<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>fi = pi()\/2; <\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>T = 0.07;<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>w=314;<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>for n = 1: <\/em><em>tz<\/em><em>*10000<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em> t(n) = (n-1)*1e-4; <\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>iok<\/em><em>(n) = Im*(sin(w*t(n)+psi-fi));<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>inok<\/em><em>(n)=Im*(<\/em><em>exp<\/em><em>(((-t(n))\/T)))*sin(psi-fi);<\/em><\/p>\r\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>end<\/em><\/p>\r\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">An exemplary course of short-circuit current is shown in Fig. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">5<\/span><span xml:lang=\"en-US\" lang=\"en-US\">.<\/span><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: center\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image17.jpeg\" alt=\"image\" width=\"377.878215223097px\" height=\"283.408713910761px\" \/><\/p>\r\n<p class=\"import-Normal\" style=\"text-align: center\"><span xml:lang=\"en-US\" lang=\"en-US\">Fig 5<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">An exemplary course of short-circuit current<\/span><\/p>\r\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The Simpson equation should be used to calculate the substitute short-circuit current value<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> (17).<\/span><\/p>\r\n<p id=\"NnljjKN\"><img class=\"alignnone size-full wp-image-97 \" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c93612452a8c.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <span xml:lang=\"en-US\" lang=\"en-US\">(17)<\/span><\/p>\r\n<p class=\"import-Nagwek1\"><strong><a id=\"_Toc2847058\"><\/a><span xml:lang=\"en-US\" lang=\"en-US\">Report<\/span><\/strong><\/p>\r\n<p class=\"import-Normal\">Report must contain at least:<\/p>\r\n\r\n<ul>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Scheme of a system<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Equivalent scheme of a system (short-circuit scheme)<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">normal operation calculations and short circuit calculations<\/span><\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">selection of indicated electrical devices (catalog sheets)<\/span><\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">short circuit current waveform on the low voltage side<\/span><\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\">calculation<\/span><span class=\"import-tlid-translation\"> of <\/span><span class=\"import-tlid-translation\">short<\/span> <span class=\"import-tlid-translation\">circuit<\/span> <span class=\"import-tlid-translation\">current<\/span><\/li>\r\n<\/ul>\r\n<p class=\"import-Nagwek1\"><strong><a id=\"_Toc2847059\"><\/a>References<\/strong><\/p>\r\n\r\n<ol>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60050 International Electrotechnical Vocabulary (IEV)<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60909-0:2016 Short-circuit currents in three-phase a.c. systems - Part 0: Calculation of currents<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60865-1:2011 Short-circuit currents - Calculation of effects - Part 1: Definitions and calculation methods<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEEE Std 551-2006 IEEE Recommended Practice for Calculating Short-Circuit Currents in Industrial and Commercial Power Systems<\/li>\r\n \t<li class=\"import-Akapitzlist\" style=\"text-align: justify\">B. de Metz-Noblat, F. Dumas, Ch. Poulain, \u201eCahier technique no. 158 Calculation of short-circuit currents\u201d, Schneider Electric<\/li>\r\n<\/ol>\r\n<\/div>","rendered":"<div class=\"__UNKNOWN__\">\n<p class=\"import-Normal\" style=\"text-align: center\"><span xml:lang=\"en-US\" lang=\"en-US\">SHORT CIRCUIT CALCULATIONS \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">EXERCISE<\/span><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image1.png\" alt=\"image\" width=\"604.8px\" height=\"342.322099737533px\" \/><\/p>\n<p><a id=\"_Toc2847051\"><\/a><strong>Aim of the excercise<\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The main purpose of the exercise is to familiarize students with the model example of short circuit calculations. It is proposed to perform the exercise on the basis of the actual power system. Short-circuit calculations are the basis for the selection of electrical apparatus and devices.<\/span><\/p>\n<p><strong>Basic information<\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\">Short-circuit is defined as a disturbance consisting in the connection of power network points with different potentials, resulting from the loss of insulating properties of its elements. It is accidental or intentional conductive path between two or more conductive parts forcing the electric potential differences between these conductive parts to be equal or close to zero.<\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\">Electrical installations nearly always require protection against short-circuits. The short-circuit current have to be calculated at each level in the installation for determining the characteristic parameters of the equipment required to withstand or break the fault current.<\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\">Calculation of normal operation conditions and short circuit calculations are made on the basis of electrical standards:<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60050 International Electrotechnical Vocabulary (IEV)<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60909-0:2016 Short-circuit currents in three-phase a.c. systems &#8211; Part 0: Calculation of currents<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60865-1:2011 Short-circuit currents &#8211; Calculation of effects &#8211; Part 1: Definitions and calculation methods<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEEE Std 551-2006 IEEE Recommended Practice for Calculating Short-Circuit Currents in Industrial and Commercial Power Systems<\/li>\n<\/ul>\n<p class=\"import-Nagwek1\"><strong><a id=\"_Toc2847053\"><\/a><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The rules for calculating the characteristic parameters of normal operation<\/span><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The basic parameters for normal operation for the calculation of the selection of electrical apparatus and devices are shown in Table 1.<\/span><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Table 1. The basic parameters for normal operation for the calculation of the selection of electrical apparatus and devices<\/span><\/p>\n<table>\n<tbody>\n<tr class=\"Tabela-Siatka-R\" style=\"height: 22.5pt\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Characteristic<\/strong> <strong>parameter<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\" colspan=\"2\">\n<p class=\"import-Normal\" style=\"text-align: center\"><strong>Equation<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Nominal (rated) voltage<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: none windowtext 0pt;border-left: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><span style=\"font-size: 14pt;color: #;text-decoration: none\">Un\u2265U<sub>n_grid<\/sub><\/span><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: solid windowtext 0.5pt;border-left: none windowtext 0pt\">\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">Un <\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">rated voltage of a device<\/span><\/div>\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">Un_grid <\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">rated voltage of a grid, where the device is placed<\/span><\/div>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\" style=\"height: 62.7pt\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Nominal (rated) current<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: none windowtext 0pt;border-left: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><span style=\"font-size: 14pt;color: #;text-decoration: none\">I<sub>n<\/sub>&gt;I<sub>load<\/sub><\/span><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border-top: solid windowtext 0.5pt;border-bottom: solid windowtext 0.5pt;border-right: solid windowtext 0.5pt;border-left: none windowtext 0pt\">\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">In<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">rated current<\/span><\/div>\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">Iload<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">load current<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> based on the power of supplied device<\/span><\/div>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">The main procedure for calculating short circuit parameters for LV installation is shown on Fig. 1.<\/p>\n<p class=\"import-Normal\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image2.png\" alt=\"image\" width=\"604.8px\" height=\"411.533333333333px\" \/><\/p>\n<p class=\"import-Normal\">Fig. 1. Short-circuit (<em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>sc<\/em><\/sub>) calculation procedure for low-voltage electrical installation (ST &#8211; short time; Inst. &#8211; instantaneous)[5]<\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\">The main characteristics of short-circuits are:<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Duration (self-extinguishing, transient and steady-state)<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Origin: mechanical (break in a conductor, accidental electrical contact between two conductors via a foreign conducting body such as a tool or an animal), internal (switching) or atmospheric overvoltages, insulation breakdown due to heat, humidity or a corrosive environment<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Location<\/li>\n<\/ul>\n<p class=\"import-Normal\" style=\"text-align: justify\">There can be different types of a short-circuit: phase-to-eartch (80% of faults), phase-to-phase (15% of faults), three-phase (5% of faults).<\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\">Electrical devices should withstand both thermal and electrodynamic short-circuit currents. In addition, apparatusses used to connect short-circuit currents should have sufficient connectivity. The proper selection of electrical equipment is based on the appropriate selection of short-circuit parameters of the power system in the place where the device is installed. The calculation of short-circuit parameters is performed for the most difficult possible short-circuit cases, i.e. for a three-phase fault directly on the circuit breaker&#8217;s terminals. The basic short-circuit parameters of electrical apparatus include:<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Peak withstand current <em>i<\/em><sub>pwc<\/sub><\/li>\n<\/ul>\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">i<sub>pwc<\/sub>\u2265i<sub>surge\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/sub><\/span>(1)<\/div>\n<p class=\"import-Normal\" style=\"margin-left: 35.45pt\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">i<sub>surge <\/sub><\/span>\u2013 surge current<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Short time withstand current <em>I<\/em><sub>k<\/sub><\/li>\n<\/ul>\n<p id=\"poWtGTg\"><img width=\"92\" height=\"55\" class=\"alignnone size-full wp-image-80\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935a99a80e5.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (2)<\/p>\n<p class=\"import-Normal\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>tz\u00a0<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">equivalent short- circuit <\/span><em lang=\"en-US\" xml:lang=\"en-US\">t<\/em><sub><em>z<\/em><\/sub><span xml:lang=\"en-US\" lang=\"en-US\">-se<\/span><span xml:lang=\"en-US\" lang=\"en-US\">conds current<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">t<sub>z<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">time of short-circuit<\/span><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\">The above inequality applies for cases where t<sub>z<\/sub>\u2265n<span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">If <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">t<sub>z<\/sub>&lt;n<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><span xml:lang=\"en-US\" lang=\"en-US\">then the apparatus or a device should be selected like for <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">t<sub>z<\/sub>=n <\/span><span xml:lang=\"en-US\" lang=\"en-US\">or its selection should be made according to the manufacturer<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">The duration of the short-circuit is determined by the circuit breaker nearest to the fault location<\/span><span xml:lang=\"en-US\" lang=\"en-US\">.<\/span><\/p>\n<p class=\"import-Normal\"><strong>CALCULATIONS OF SHORT-CIRCUIT CURRENTS<\/strong><\/p>\n<p class=\"import-Normal\">a) Initial short-circuit current <span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>peak<\/sub><\/span><\/p>\n<p id=\"Ucvogoi\"><img class=\"alignnone wp-image-81\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935b9a1755a.png\" alt=\"\" width=\"217\" height=\"52\" \/> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 (3)<\/p>\n<p class=\"import-Normal\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">U<sub>n <\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">nominal (rated) voltage of a grid<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><em lang=\"en-US\" xml:lang=\"en-US\">k<\/em> \u2013 factor depending on the load of a system; for typical cases it is assumed as <em lang=\"en-US\" xml:lang=\"en-US\">k<\/em> = 1,1, <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> \u2013 <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">factor depending on the type of fault; for a three-phase fault<\/span> <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> = 1<\/p>\n<p class=\"import-Normal\">b) Surge current <em>I<sub>surge<\/sub><\/em><\/p>\n<div>\n<p><img class=\"alignnone wp-image-82\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935bb634fcb.png\" alt=\"\" width=\"205\" height=\"33\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (4)<\/p>\n<\/div>\n<p class=\"import-Normal\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">k<sub>u<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">coefficient determined from Fig. 2<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>peak<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">initial short-circuit current<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> \u2013 <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">factor depending on the type of fault; for a three-phase fault<\/span> <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> = 1<\/p>\n<p class=\"import-Normal\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image4.png\" alt=\"image\" width=\"604.8px\" height=\"278.030551181102px\" \/><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\">Fig 2. Dependence of an coefficient <em lang=\"en-US\" xml:lang=\"en-US\">k<\/em><sub><em>u<\/em><\/sub> from the quotient <em lang=\"en-US\" xml:lang=\"en-US\">R<\/em> and <em lang=\"en-US\" xml:lang=\"en-US\">X<\/em><\/p>\n<p>c) Rated short-time withstand current <em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>th1s<\/em><\/sub><\/p>\n<p id=\"OpTpIJE\"><img class=\"alignnone wp-image-83\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935bed919d1.png\" alt=\"\" width=\"147\" height=\"39\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (5)<\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\">where: <span style=\"font-size: NaNpt;color: #;text-decoration: none\">k<sub>c <\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\">\u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">coefficient taking into account the disappearance of the periodic current component during short circuit determined from Fig. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">3, <\/span><span style=\"font-size: NaNpt;color: #;text-decoration: none\">I<sub>peak<\/sub><\/span><span xml:lang=\"en-US\" lang=\"en-US\"> \u2013 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">initial short-circuit current<\/span><span xml:lang=\"en-US\" lang=\"en-US\">, <\/span><em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> \u2013 factor depending on the type of fault; for a three-phase fault <em lang=\"en-US\" xml:lang=\"en-US\">m<\/em> = 1<\/p>\n<div class=\"wp-nocaption wp-image-85 aligncenter\"><img class=\"wp-image-85 aligncenter\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935ca77eed5.png\" alt=\"\" width=\"474\" height=\"595\" \/><\/div>\n<p class=\"import-Normal\" style=\"text-align: center\">Fig. 3. Dependence of the coefficient <em lang=\"en-US\" xml:lang=\"en-US\">k<\/em><sub><em>c<\/em><\/sub> from quotient <em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>1<\/em><\/sub> and <em lang=\"en-US\" xml:lang=\"en-US\">I<\/em><sub><em>n<\/em><\/sub> and the time of short-circuit <em lang=\"en-US\" xml:lang=\"en-US\">t<\/em><sub><em>z<\/em><\/sub> [PN-E-05002:1974]<\/p>\n<p class=\"import-Normal\" style=\"text-align: justify;text-indent: 42.55pt\">Coefficient k<sub>c<\/sub> is determined from Fig. 3 <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">and depends on the duration of the fault and the ratio of the component of the <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">initial short-circuit<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> current and the sum of currents from all sources that can <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">supply<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> the short circuit. In the case of fault duration with a value other than those specified in Fig. 3, linear interpolation should be used.<\/span><\/p>\n<p class=\"import-Nagwek2\"><a id=\"_Toc2847054\"><\/a><strong>Calculations for selection of current transformers<\/strong><\/p>\n<p>a) Current of primary side of current transformer<\/p>\n<div class=\"wp-nocaption alignnone wp-image-86\"><img class=\"alignnone wp-image-86\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935dad629c8.png\" alt=\"\" width=\"144\" height=\"50\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <span xml:lang=\"en-US\" lang=\"en-US\">(6)<\/span><\/div>\n<p>b) Load power<\/p>\n<p id=\"KCSwskq\"><img class=\"alignnone wp-image-87\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935dcfe9da0.png\" alt=\"\" width=\"315\" height=\"39\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 \u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (7)<\/p>\n<p class=\"import-Normal\">gdzie: <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>cables<\/em><\/sub> \u2013 power of losses from cables, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>measurement<\/em><\/sub> \u2013 power of losses from measurement device, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>contacts<\/em><\/sub> \u2013 power of losses from contacts<\/p>\n<p class=\"import-Normal\">It can be assumed that:<\/p>\n<ul>\n<li class=\"import-Normal\">Power losses on measurement device are 0,01 VA<\/li>\n<li class=\"import-Normal\">Power losses on contacts are 1,25 VA<\/li>\n<li class=\"import-Normal\">Power losses on cables need to be calculated from (8)<\/li>\n<\/ul>\n<div>\n<p><img width=\"97\" height=\"52\" class=\"alignnone size-full wp-image-88\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935e6f46c83.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (8)<\/p>\n<\/div>\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The correct choice of parameters consists in checking inequalities<\/span> <span xml:lang=\"en-US\" lang=\"en-US\">(9) <\/span><span xml:lang=\"en-US\" lang=\"en-US\">and<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> (10).<\/span><\/p>\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">0,25\u2219S<sub>N<\/sub>\u2264S<sub>obl<\/sub>\u2264S<sub>N<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">(9)<\/span><\/div>\n<div><span style=\"font-size: NaNpt;color: #;text-decoration: none\">0,6\u2219I<sub>Np<\/sub>\u2264I<sub>obl<\/sub>\u22641,2\u2219I<sub>Np<\/sub>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span xml:lang=\"en-US\" lang=\"en-US\">(10)<\/span><\/div>\n<p class=\"import-Nagwek2\"><strong><a id=\"_Toc2847055\"><\/a><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Selection of voltage measuring transformers in MV networks<\/span><\/strong><\/p>\n<p>a) Voltage of primary side<\/p>\n<div>\n<p><img class=\"alignnone wp-image-89\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935eb6bf9e1.png\" alt=\"\" width=\"103\" height=\"43\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (11)<\/p>\n<\/div>\n<p>b) Rated isolation level<\/p>\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Due to the nominal primary voltage of the transformer, <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">eg<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> in MV networks, the rated is<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">o<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">lation level should be selected as<\/span> 17,5\/38\/95, where:<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">17,5 kV \u2013 highest possible voltage (RMS)<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">38 kV \u2013 rated short-time test voltage on network frequency (RMS)<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">95 kV \u2013 rated test lighting voltage (max value))<\/li>\n<\/ul>\n<p><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">c) Rated secondary voltage of the measuring transformer depending on the connection system<\/span><\/p>\n<div>\n<p><img width=\"107\" height=\"48\" class=\"alignnone size-full wp-image-90\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935f1c2b5dc.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (12)<\/p>\n<\/div>\n<p>d) Load power<\/p>\n<p><img class=\"alignnone wp-image-87\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c935dcfe9da0.png\" alt=\"\" width=\"315\" height=\"39\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (13)<\/p>\n<p class=\"import-Normal\">gdzie: <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>cables<\/em><\/sub> \u2013 power of losses from cables, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>measurement<\/em><\/sub> \u2013 power of losses from measurement device, <em lang=\"en-US\" xml:lang=\"en-US\">S<\/em><sub><em>contacts<\/em><\/sub> \u2013 power of losses from contacts<\/p>\n<p class=\"import-Normal\">It can be assumed that:<\/p>\n<ul>\n<li class=\"import-Normal\">Power losses on measurement device are 0,01 VA<\/li>\n<li class=\"import-Normal\">Power losses on contacts are 1,25 VA<\/li>\n<li class=\"import-Normal\">Power losses on cables need to be calculated from (8)<\/li>\n<\/ul>\n<p class=\"import-Nagwek2\"><strong><a id=\"_Toc2847056\"><\/a><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> calculation<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> task of choosing electrical devices<\/span><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\">On the <\/span><span class=\"import-tlid-translation\">basis<\/span><span class=\"import-tlid-translation\"> of Fig. <\/span><span class=\"import-tlid-translation\">4<\/span><span class=\"import-tlid-translation\">, <\/span><span class=\"import-tlid-translation\">appropriate<\/span> <span class=\"import-tlid-translation\">electrical<\/span> <span class=\"import-tlid-translation\">equipment<\/span> <span class=\"import-tlid-translation\">should<\/span><span class=\"import-tlid-translation\"> be <\/span><span class=\"import-tlid-translation\">selected<\/span><span class=\"import-tlid-translation\">. The system <\/span><span class=\"import-tlid-translation\">is<\/span> <span class=\"import-tlid-translation\">powered<\/span><span class=\"import-tlid-translation\"> from MV network with GPZ with 3x <\/span><span class=\"import-tlid-translation\">XRUHAKXs<\/span><span class=\"import-tlid-translation\"> 1&#215;240 mm2 cables. The MV <\/span><span class=\"import-tlid-translation\">switchgear<\/span> <span class=\"import-tlid-translation\">is<\/span> <span class=\"import-tlid-translation\">constructed<\/span><span class=\"import-tlid-translation\"> from <\/span><span class=\"import-tlid-translation\">two<\/span> <span class=\"import-tlid-translation\">sections<\/span><span class=\"import-tlid-translation\">; from <\/span><span class=\"import-tlid-translation\">each<\/span> <span class=\"import-tlid-translation\">section<\/span><span class=\"import-tlid-translation\">, 4 <\/span><span class=\"import-tlid-translation\">dry<\/span> <span class=\"import-tlid-translation\">transformers<\/span><span class=\"import-tlid-translation\"> 15 \/ 0.4 <\/span><span class=\"import-tlid-translation\">kV<\/span> <span class=\"import-tlid-translation\">are<\/span> <span class=\"import-tlid-translation\">supplied<\/span> <span class=\"import-tlid-translation\">through<\/span><span class=\"import-tlid-translation\"> MV <\/span><span class=\"import-tlid-translation\">circuit<\/span> <span class=\"import-tlid-translation\">breakers<\/span><span class=\"import-tlid-translation\"> and 3x <\/span><span class=\"import-tlid-translation\">XRUHAKXs<\/span><span class=\"import-tlid-translation\"> 1 x 120 mm2 <\/span><span class=\"import-tlid-translation\">cable<\/span><span class=\"import-tlid-translation\"> lines. <\/span><span class=\"import-tlid-translation\">From<\/span> <span class=\"import-tlid-translation\">transformers<\/span> <span class=\"import-tlid-translation\">are<\/span> <span class=\"import-tlid-translation\">powered<\/span> <span class=\"import-tlid-translation\">low<\/span> <span class=\"import-tlid-translation\">voltage<\/span> <span class=\"import-tlid-translation\">switchgears<\/span><span class=\"import-tlid-translation\"> via LV <\/span><span class=\"import-tlid-translation\">switches<\/span>.<\/p>\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\">For the <\/span><span class=\"import-tlid-translation\">short-circuit<\/span> <span class=\"import-tlid-translation\">loop<\/span> <span class=\"import-tlid-translation\">impedance<\/span> <span class=\"import-tlid-translation\">calculation<\/span><span class=\"import-tlid-translation\">, <\/span><span class=\"import-tlid-translation\">use<\/span><span class=\"import-tlid-translation\"> the <\/span><span class=\"import-tlid-translation\">following<\/span> <span class=\"import-tlid-translation\">relationships<\/span>:<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">For cables<\/li>\n<\/ul>\n<p id=\"bgrtbQQ\"><img class=\"alignnone wp-image-91\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c9360294a69e.png\" alt=\"\" width=\"74\" height=\"54\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 (14)<\/p>\n<p class=\"import-Normal\">where: &#8211; unit cable resistance, &#8211; reaktancja jednostkowa linii kablowej<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">for two-windings (MV\/LV) transformers<\/li>\n<\/ul>\n<p id=\"jRwnBPF\"><img class=\"alignnone wp-image-93\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c93605775223.png\" alt=\"\" width=\"138\" height=\"111\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (15)<\/p>\n<p class=\"import-Normal\">where:\u00a0\u0394U<sub>zw%<\/sub> &#8211; impedance voltage at rated current, \u0394P<sub>R(kW)<\/sub>&#8211; <span class=\"import-tlid-translation\">rated<\/span> <span class=\"import-tlid-translation\">load<\/span> <span class=\"import-tlid-translation\">power<\/span> <span class=\"import-tlid-translation\">losses<\/span><\/p>\n<p class=\"import-Normal\"><strong>ATTENTION!!<\/strong><\/p>\n<p class=\"import-Normal\">When setting an impedance substitute circuit, it is important to remember that the impedance of individual elements must relate to one voltage level!<\/p>\n<p id=\"oJVubsa\"><img width=\"121\" height=\"73\" class=\"alignnone size-full wp-image-96\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c9360e4c567c.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (16)<\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image16.png\" alt=\"image\" width=\"811.777952755906px\" height=\"573.6px\" \/><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><span xml:lang=\"en-US\" lang=\"en-US\">Fig<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">4<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Diagram of the power supply system for the task of choosing electrical devices<\/span><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\">The data for the <\/span><span class=\"import-tlid-translation\">task<\/span> <span class=\"import-tlid-translation\">is<\/span><span class=\"import-tlid-translation\"> set out in <\/span><span class=\"import-tlid-translation\">Tables<\/span><span class=\"import-tlid-translation\"> 2-5. The <\/span><span class=\"import-tlid-translation\">duration<\/span><span class=\"import-tlid-translation\"> of the <\/span><span class=\"import-tlid-translation\">short<\/span> <span class=\"import-tlid-translation\">circuit<\/span><span class=\"import-tlid-translation\"> in the <\/span><span class=\"import-tlid-translation\">low<\/span> <span class=\"import-tlid-translation\">voltage<\/span><span class=\"import-tlid-translation\"> network <\/span><span class=\"import-tlid-translation\">should<\/span><span class=\"import-tlid-translation\"> be <\/span><span class=\"import-tlid-translation\">taken<\/span> <span class=\"import-tlid-translation\">at<\/span><span class=\"import-tlid-translation\"> 0.4 s<\/span>.<\/p>\n<p class=\"import-Normal\"><span xml:lang=\"en-US\" lang=\"en-US\">Tab<\/span><span xml:lang=\"en-US\" lang=\"en-US\">le<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> 2. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Basic data for the <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">calculation <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">task<\/span><\/p>\n<table style=\"width: 616px\">\n<tbody>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\"><strong>Team No<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\"><strong lang=\"en-US\" xml:lang=\"en-US\">Power of a system<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> [MVA]<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\"><strong>Indicated<\/strong><strong> transformer<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\"><strong lang=\"en-US\" xml:lang=\"en-US\">Short-circuit time in MV grid<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> [s]<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\"><strong class=\"import-tlid-translation\" lang=\"en-US\" xml:lang=\"en-US\">Short circuit power<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> of a system<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\">\u2013 <\/strong><strong lang=\"en-US\" xml:lang=\"en-US\">multiplier<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">50<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,6<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">2<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">60<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">3<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">80<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">4<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">90<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,0<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">1,5<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">5<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">120<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">0,8<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">2,5<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">6<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">85<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">0,9<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">7<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">7<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">75<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">0,7<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">5<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">8<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">55<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">0,5<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">10<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">9<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">65<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,0<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">3,5<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">10<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">45<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,5<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">5<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">11<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">90<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">6<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 54.9667px\">\n<p class=\"import-Normal\">12<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 129.367px\">\n<p class=\"import-Normal\">110<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 125.8px\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 108.433px\">\n<p class=\"import-Normal\">1,1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: 0.5pt solid windowtext;width: 141.433px\">\n<p class=\"import-Normal\">5,5<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 54.9667px\"><\/td>\n<td style=\"width: 129.367px\"><\/td>\n<td style=\"width: 125.8px\"><\/td>\n<td style=\"width: 108.433px\"><\/td>\n<td style=\"width: 141.433px\"><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\"><span xml:lang=\"en-US\" lang=\"en-US\">Tab<\/span><span xml:lang=\"en-US\" lang=\"en-US\">le<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> 3. <\/span><span xml:lang=\"en-US\" lang=\"en-US\">Rated parameters of transformers<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> 15\/0,4 kV<\/span><\/p>\n<table>\n<tbody>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>Indicated<\/strong><strong> transformer<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>Nominal<\/strong><strong> (<\/strong><strong>rated<\/strong><strong>) <\/strong><strong>power<\/strong><strong> [<\/strong><strong>kVA<\/strong><strong>]<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>I<\/strong><strong>mpedance<\/strong> <strong>voltage<\/strong> <strong>at<\/strong> <strong>rated<\/strong> <strong>current<\/strong> <strong>[%]<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>Rated<\/strong> <strong>load<\/strong> <strong>power<\/strong> <strong>losses<\/strong><strong> [W]<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong class=\"import-tlid-translation\">The <\/strong><strong class=\"import-tlid-translation\">length<\/strong><strong class=\"import-tlid-translation\"> of the <\/strong><strong class=\"import-tlid-translation\">cable<\/strong> <strong class=\"import-tlid-translation\">line<\/strong> <strong class=\"import-tlid-translation\">powering<\/strong><strong class=\"import-tlid-translation\"> the <\/strong><strong class=\"import-tlid-translation\">device<\/strong> <strong>[m]<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">2000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">16000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1000<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1600<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">6<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">13000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">800<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">8<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">9000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">850<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 1 \u2013 trafo 4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">3150<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">10<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">22000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">700<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">3150<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">22000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1100<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">6<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">9000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">560<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1600<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">8<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">13000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">485<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">Section 2 \u2013 trafo 4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">2000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">10<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">16000<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1050<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Table 4. <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">Additional parameters to complete the task<\/span><\/p>\n<table>\n<tbody>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>No in team<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong lang=\"el-GR\" xml:lang=\"el-GR\">\u03c8<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong lang=\"en-US\" xml:lang=\"en-US\">Length of a cable<\/strong><strong lang=\"en-US\" xml:lang=\"en-US\"> L1 [m]<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">3,5<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">200<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">2<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">3,3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">250<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">3<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">3,1<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">150<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">4<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">2,8<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">320<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Normal\">Table 5. <span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The rated parameters of cable lines<\/span><\/p>\n<table>\n<tbody>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>Cable<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>Unit <\/strong><strong>resistance<\/strong><strong> [<\/strong><strong>\u2126<\/strong><strong>\/km]<\/strong><\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\"><strong>Unit reactance<\/strong><strong> [<\/strong><strong>\u2126<\/strong><strong>\/km]<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">XRUHAKXs 1&#215;240<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">0,125<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">0,58<\/p>\n<\/td>\n<\/tr>\n<tr class=\"Tabela-Siatka-R\">\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">XRUHAKXs 1&#215;120<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">0,253<\/p>\n<\/td>\n<td class=\"Tabela-Siatka-C\" style=\"border: solid windowtext 0.5pt\">\n<p class=\"import-Normal\">0,182<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td><\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"import-Nagwek2\"><strong><a id=\"_Toc2847057\"><\/a><span class=\"import-tlid-translation\">Short-circuit<\/span> <span class=\"import-tlid-translation\">current<\/span> <span class=\"import-tlid-translation\">course<\/span><\/strong><\/p>\n<p class=\"import-Normal\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">You can use the MATLAB software and the script below to plot the short-circuit current. The output data is: the effective value of the short-circuit current in kA, the phase of current switching <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">in<\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\"> rad, the short-circuit time in s<\/span>.<\/p>\n<p class=\"import-Normal\">MATLAB programme<\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-GB\" xml:lang=\"en-GB\">clear all;<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-GB\" xml:lang=\"en-GB\">close all;<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>clc<\/em><em>;<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>format compact;<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-US\" xml:lang=\"en-US\">disp<\/em><em lang=\"en-US\" xml:lang=\"en-US\">(&#8216;<\/em><em lang=\"en-US\" xml:lang=\"en-US\">T<\/em><em lang=\"en-US\" xml:lang=\"en-US\">he effective value of the short-circuit current <\/em><em lang=\"en-US\" xml:lang=\"en-US\">[kA]&#8217;);<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>I = <\/em><em>input<\/em><em>(&#8216;I = &#8216;);<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-US\" xml:lang=\"en-US\">disp<\/em><em lang=\"en-US\" xml:lang=\"en-US\">(&#8216;<\/em><em lang=\"en-US\" xml:lang=\"en-US\">Phase of current <\/em><em lang=\"en-US\" xml:lang=\"en-US\">switching<\/em><em lang=\"en-US\" xml:lang=\"en-US\">w<\/em><em lang=\"en-US\" xml:lang=\"en-US\"> [rad]&#8217;);<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>psi = <\/em><em>input<\/em><em>(&#8216;psi = &#8216;);<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em lang=\"en-US\" xml:lang=\"en-US\">disp<\/em><em lang=\"en-US\" xml:lang=\"en-US\">(&#8216;<\/em><em lang=\"en-US\" xml:lang=\"en-US\">Short-circuit <\/em><em lang=\"en-US\" xml:lang=\"en-US\">time<\/em><em lang=\"en-US\" xml:lang=\"en-US\">w<\/em><em lang=\"en-US\" xml:lang=\"en-US\"> [s]&#8217;);<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>tz<\/em><em> = <\/em><em>input<\/em><em>(&#8216;<\/em><em>tz<\/em><em> = &#8216;);<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>Im = I*<\/em><em>sqrt<\/em><em>(2)*1e3;<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>fi = pi()\/2; <\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>T = 0.07;<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>w=314;<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>for n = 1: <\/em><em>tz<\/em><em>*10000<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em> t(n) = (n-1)*1e-4; <\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>iok<\/em><em>(n) = Im*(sin(w*t(n)+psi-fi));<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>inok<\/em><em>(n)=Im*(<\/em><em>exp<\/em><em>(((-t(n))\/T)))*sin(psi-fi);<\/em><\/p>\n<p class=\"import-Normal\" style=\"margin-left: 56.7pt\"><em>end<\/em><\/p>\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">An exemplary course of short-circuit current is shown in Fig. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">5<\/span><span xml:lang=\"en-US\" lang=\"en-US\">.<\/span><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><img src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/image17.jpeg\" alt=\"image\" width=\"377.878215223097px\" height=\"283.408713910761px\" \/><\/p>\n<p class=\"import-Normal\" style=\"text-align: center\"><span xml:lang=\"en-US\" lang=\"en-US\">Fig 5<\/span><span xml:lang=\"en-US\" lang=\"en-US\">. <\/span><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">An exemplary course of short-circuit current<\/span><\/p>\n<p class=\"import-Normal\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">The Simpson equation should be used to calculate the substitute short-circuit current value<\/span><span xml:lang=\"en-US\" lang=\"en-US\"> (17).<\/span><\/p>\n<p id=\"NnljjKN\"><img width=\"495\" height=\"62\" class=\"alignnone size-full wp-image-97\" src=\"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-content\/uploads\/sites\/11\/2019\/03\/img_5c93612452a8c.png\" alt=\"\" \/>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <span xml:lang=\"en-US\" lang=\"en-US\">(17)<\/span><\/p>\n<p class=\"import-Nagwek1\"><strong><a id=\"_Toc2847058\"><\/a><span xml:lang=\"en-US\" lang=\"en-US\">Report<\/span><\/strong><\/p>\n<p class=\"import-Normal\">Report must contain at least:<\/p>\n<ul>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Scheme of a system<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">Equivalent scheme of a system (short-circuit scheme)<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">normal operation calculations and short circuit calculations<\/span><\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">selection of indicated electrical devices (catalog sheets)<\/span><\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\" xml:lang=\"en-US\" lang=\"en-US\">short circuit current waveform on the low voltage side<\/span><\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\"><span class=\"import-tlid-translation\">calculation<\/span><span class=\"import-tlid-translation\"> of <\/span><span class=\"import-tlid-translation\">short<\/span> <span class=\"import-tlid-translation\">circuit<\/span> <span class=\"import-tlid-translation\">current<\/span><\/li>\n<\/ul>\n<p class=\"import-Nagwek1\"><strong><a id=\"_Toc2847059\"><\/a>References<\/strong><\/p>\n<ol>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60050 International Electrotechnical Vocabulary (IEV)<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60909-0:2016 Short-circuit currents in three-phase a.c. systems &#8211; Part 0: Calculation of currents<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEC 60865-1:2011 Short-circuit currents &#8211; Calculation of effects &#8211; Part 1: Definitions and calculation methods<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">IEEE Std 551-2006 IEEE Recommended Practice for Calculating Short-Circuit Currents in Industrial and Commercial Power Systems<\/li>\n<li class=\"import-Akapitzlist\" style=\"text-align: justify\">B. de Metz-Noblat, F. Dumas, Ch. Poulain, \u201eCahier technique no. 158 Calculation of short-circuit currents\u201d, Schneider Electric<\/li>\n<\/ol>\n<\/div>\n","protected":false},"author":10,"menu_order":1,"template":"","meta":{"pb_show_title":"on","pb_short_title":"SHORT CIRCUIT CALCULATIONS \u2013 EXERCISE","pb_subtitle":"","pb_authors":["elap"],"pb_section_license":"all-rights-reserved"},"chapter-type":[47],"contributor":[60],"license":[58],"part":3,"_links":{"self":[{"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/pressbooks\/v2\/chapters\/75"}],"collection":[{"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/wp\/v2\/users\/10"}],"version-history":[{"count":7,"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/pressbooks\/v2\/chapters\/75\/revisions"}],"predecessor-version":[{"id":210,"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/pressbooks\/v2\/chapters\/75\/revisions\/210"}],"part":[{"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/pressbooks\/v2\/parts\/3"}],"metadata":[{"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/pressbooks\/v2\/chapters\/75\/metadata\/"}],"wp:attachment":[{"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/wp\/v2\/media?parent=75"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/pressbooks\/v2\/chapter-type?post=75"},{"taxonomy":"contributor","embeddable":true,"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/wp\/v2\/contributor?post=75"},{"taxonomy":"license","embeddable":true,"href":"http:\/\/pb.ee.pw.edu.pl\/pb\/elap\/wp-json\/wp\/v2\/license?post=75"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}