{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Chapter 33: PROTECTIVE RELAYS" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 33.1: Time_of_operation_of_the_relay.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "// A Texbook on POWER SYSTEM ENGINEERING\n", "// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar\n", "// DHANPAT RAI & Co.\n", "// SECOND EDITION \n", "\n", "// PART III : SWITCHGEAR AND PROTECTION\n", "// CHAPTER 7: PROTECTIVE RELAYS\n", "\n", "// EXAMPLE : 7.1 :\n", "// Page number 595-596\n", "clear ; clc ; close ; // Clear the work space and console\n", "\n", "// Given data\n", "I_setting = 150.0 // Current setting of IDMT(%)\n", "t_mult = 0.5 // Time multiplier setting\n", "ratio_CT = 500.0/5 // CT ratio\n", "CT_sec = 5.0 // Secondary turn\n", "I_f = 6000.0 // Fault current\n", "\n", "// Calculations\n", "I_sec_fault = I_f/ratio_CT // Secondary fault current(A)\n", "PSM = I_sec_fault/(CT_sec*I_setting/100) // Plug setting multiplier\n", "t = 3.15 // Time against this PSM(sec). From graph E7.1 in textbook page no 595\n", "time_oper = t*t_mult // Operating time(sec)\n", "\n", "// Results\n", "disp('PART III - EXAMPLE : 7.1 : SOLUTION :-')\n", "printf('\nTime of operation of the relay = %.3f sec', time_oper)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 33.2: Time_of_operation_of_the_relay.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "// A Texbook on POWER SYSTEM ENGINEERING\n", "// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar\n", "// DHANPAT RAI & Co.\n", "// SECOND EDITION \n", "\n", "// PART III : SWITCHGEAR AND PROTECTION\n", "// CHAPTER 7: PROTECTIVE RELAYS\n", "\n", "// EXAMPLE : 7.2 :\n", "// Page number 596\n", "clear ; clc ; close ; // Clear the work space and console\n", "\n", "// Given data\n", "ratio = 525.0/1 // CT ratio\n", "CT_sec = 1.0 // Secondary turn\n", "t_mult = 0.3 // Time multiplier setting\n", "I_f = 5250.0 // Fault current(A)\n", "\n", "// Calculations\n", "I_sec_fault = I_f/ratio // Secondary fault current(A)\n", "PSM = I_sec_fault/(1.25*CT_sec) // Plug setting multiplier\n", "t = 3.15 // Time against this PSM(sec). From graph E7.1 in textbook page no 595\n", "time_oper = t*t_mult // Operating time(sec)\n", "\n", "// Results\n", "disp('PART III - EXAMPLE : 7.2 : SOLUTION :-')\n", "printf('\nTime of operation of the relay = %.3f sec', time_oper)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 33.3: EX33_3.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "// A Texbook on POWER SYSTEM ENGINEERING\n", "// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar\n", "// DHANPAT RAI & Co.\n", "// SECOND EDITION \n", "\n", "// PART III : SWITCHGEAR AND PROTECTION\n", "// CHAPTER 7: PROTECTIVE RELAYS\n", "\n", "// EXAMPLE : 7.3 :\n", "// Page number 596\n", "clear ; clc ; close ; // Clear the work space and console\n", "\n", "// Given data\n", "MVA = 20.0 // Transformer MVA\n", "overload = 30.0 // Overload of transformer(%)\n", "kV = 11.0 // Bus bar rating(kV)\n", "CT_trans = 1000.0/5 // Transformer CT\n", "CT_cb = 400.0/5 // Circuit breaker CT\n", "ps = 125.0 // Plug setting(%)\n", "ts = 0.3 // Time setting\n", "I_f = 5000.0 // Fault current(A)\n", "t_margin = 0.5 // Discriminative time margin(sec)\n", "\n", "// Calculations\n", "I_sec_fault = I_f/CT_cb // Secondary fault current(A)\n", "CT_cb_sec = 5.0 // Secondary turn\n", "PSM = I_sec_fault/(ps/100*CT_cb_sec) // Plug setting multiplier\n", "t = 2.8 // Time against this PSM(sec). From graph E7.1 in textbook page no 595\n", "time_oper = t*ts // Operating time of feeder relay(sec)\n", "I_ol = (1+(overload/100))*MVA*1000/(3**0.5*kV) // Overload current(A)\n", "I_sec_T = I_ol/CT_trans // Secondary current(A)\n", "CT_T_sec = 5.0 // Secondary turn of transformer\n", "PSM_T = I_sec_T/CT_T_sec // Minimum plug setting multiplier of transformer\n", "I_sec_T1 = I_f/CT_trans // Secondary fault current(A)\n", "ps_T1 = 1.5 // Plug setting as per standard value\n", "PSM_T1 = I_sec_T1/(CT_T_sec*ps) // Plug setting multiplier of transformer\n", "t_T1 = 7.0 // Time against this PSM(sec). From graph E7.1 in textbook page no 595\n", "time_setting = (time_oper+t_margin)/t_T1 // Time setting of transformer\n", "\n", "// Results\n", "disp('PART III - EXAMPLE : 7.3 : SOLUTION :-')\n", "printf('\nOperating time of feeder relay = %.2f sec', time_oper)\n", "printf('\nMinimum plug setting of transformer relay, P.S > %.2f ', PSM_T)\n", "printf('\nTime setting of transformer = %.3f ', time_setting)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 33.4: Time_of_operation_of_the_two_relays.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "// A Texbook on POWER SYSTEM ENGINEERING\n", "// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar\n", "// DHANPAT RAI & Co.\n", "// SECOND EDITION \n", "\n", "// PART III : SWITCHGEAR AND PROTECTION\n", "// CHAPTER 7: PROTECTIVE RELAYS\n", "\n", "// EXAMPLE : 7.4 :\n", "// Page number 596-597\n", "clear ; clc ; close ; // Clear the work space and console\n", "\n", "// Given data\n", "I_f = 2000.0 // Fault current(A)\n", "ratio_CT = 200.0/1 // CT ratio\n", "R_1 = 100.0 // Relay 1 set on(%)\n", "R_2 = 125.0 // Relay 2 set on(%)\n", "t_margin = 0.5 // Discriminative time margin(sec)\n", "TSM_1 = 0.2 // Time setting multiplier of relay 1\n", "\n", "// Calculations\n", "CT_sec = 200.0 // CT secondary\n", "PSM_1 = I_f*100/(CT_sec*R_1) // PSM of relay 1\n", "t_1 = 2.8 // Time against this PSM(sec). From graph E7.1 in textbook page no 595\n", "time_oper_1 = TSM_1*t_1 // Operating time of relay with TSM of 0.2(Sec)\n", "PSM_2 = I_f*100/(CT_sec*R_2) // PSM of relay 2\n", "t_2 = 3.15 // Time against this PSM(sec). From graph E7.1 in textbook page no 595\n", "actual_time_2 = time_oper_1+t_margin // Actual time of operation of relay 2(sec)\n", "TSM_2 = actual_time_2/t_2 // Time setting multiplier of relay 2\n", "\n", "// Results\n", "disp('PART III - EXAMPLE : 7.4 : SOLUTION :-')\n", "printf('\nTime of operation of relay 1 = %.2f sec', time_oper_1)\n", "printf('\nActual time of operation of relay 2 = %.2f sec', actual_time_2)\n", "printf('\nT.S.M of relay 2 = %.4f', TSM_2)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 33.6: Will_the_relay_operate_the_trip_of_the_breaker.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "// A Texbook on POWER SYSTEM ENGINEERING\n", "// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar\n", "// DHANPAT RAI & Co.\n", "// SECOND EDITION \n", "\n", "// PART III : SWITCHGEAR AND PROTECTION\n", "// CHAPTER 7: PROTECTIVE RELAYS\n", "\n", "// EXAMPLE : 7.6 :\n", "// Page number 611\n", "clear ; clc ; close ; // Clear the work space and console\n", "\n", "// Given data\n", "I_min = 0.1 // Relay minimum pick up current(A)\n", "slope = 10.0 // Slope characteristic(%)\n", "CT_ratio = 400.0/5 // CT ratio\n", "I_1 = 320.0 // Current(A)\n", "I_2 = 304.0 // Current(A)\n", "\n", "// Calculations\n", "I_op_coil = (I_1-I_2)/CT_ratio // Current in operating coil(A)\n", "I_re_coil = 1.0*(I_1+I_2)/(2*CT_ratio) // Current in restraining coil(A)\n", "I_re_coil_slope = I_re_coil*slope/100 // Current in restraining coil with slope(A)\n", "\n", "// Results\n", "disp('PART III - EXAMPLE : 7.6 : SOLUTION :-')\n", "if(I_op_coil