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+{
+"cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Chapter 32: CIRCUIT BREAKER"
+ ]
+ },
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 32.1: EX32_1.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 6: CIRCUIT BREAKER\n",
+"\n",
+"// EXAMPLE : 6.1 :\n",
+"// Page number 545\n",
+"clear ; clc ; close ; // Clear the work space and console\n",
+"\n",
+"// Given data\n",
+"f = 50.0 // Generator frequency(Hz)\n",
+"kV = 7.5 // emf to neutral rms voltage(kV)\n",
+"X = 4.0 // Reactance of generator & connected system(ohm)\n",
+"C = 0.01*10**-6 // Distributed capacitance(F)\n",
+"\n",
+"// Calculations\n",
+"// Case(a)\n",
+"v = 2**0.5*kV // Active recovery voltage i.e phase to neutral(kV)\n",
+"V_max_restrike = v*2 // Maximum restriking voltage i.e phase to neutral(kV)\n",
+"// Case(b)\n",
+"L = X/(2.0*%pi*f) // Inductance(H)\n",
+"f_n = 1/(2.0*%pi*(L*C)**0.5*1000) // Frequency of transient oscillation(kHZ)\n",
+"// Case(c)\n",
+"t = 1.0/(2.0*f_n*1000) // Time(sec)\n",
+"avg_rate = V_max_restrike/t // Average rate of rise of voltage upto first peak of oscillation(kV/s)\n",
+"\n",
+"// Results\n",
+"disp('PART III - EXAMPLE : 6.1 : SOLUTION :-')\n",
+"printf('\nCase(a): Maximum re-striking voltage(phase-to-neutral) = %.1f kV', V_max_restrike)\n",
+"printf('\nCase(b): Frequency of transient oscillation, f_n = %.1f kHz', f_n)\n",
+"printf('\nCase(c): Average rate of rise of voltage upto first peak of oscillation = %.f kV/s \n', avg_rate)\n",
+"printf('\nNOTE: Changes in the obtained answer from that of textbook is due to more approximation in the textbook')"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 32.3: Rate_of_rise_of_restriking_voltage.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 6: CIRCUIT BREAKER\n",
+"\n",
+"// EXAMPLE : 6.3 :\n",
+"// Page number 545-546\n",
+"clear ; clc ; close ; // Clear the work space and console\n",
+"\n",
+"// Given data\n",
+"kV = 132.0 // Voltage(kV)\n",
+"pf = 0.3 // Power factor of the fault\n",
+"K3 = 0.95 // Recovery voltage was 0.95 of full line value\n",
+"f_n = 16000.0 // Natural frequency of the restriking transient(Hz)\n",
+"\n",
+"// Calculations\n",
+"kV_phase = kV/3**0.5 // System voltage(kV)\n",
+"sin_phi = sind(acosd(pf)) // Sinφ\n",
+"K2 = 1.0\n",
+"v = K2*K3*kV/3**0.5*2**0.5*sin_phi // Active recovery voltage(kV)\n",
+"V_max_restrike = 2*v // Maximum restriking voltage(kV)\n",
+"t = 1.0/(2.0*f_n) // Time(sec)\n",
+"RRRV = V_max_restrike/(t*10**6) // Rate of rise of restriking voltage(kV/µ-sec)\n",
+"\n",
+"// Results\n",
+"disp('PART III - EXAMPLE : 6.3 : SOLUTION :-')\n",
+"printf('\nRate of rise of restriking voltage, R.R.R.V = %.2f kV/µ-sec', RRRV)"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 32.5: Voltage_across_the_pole_of_a_CB_and_Resistance_to_be_used_across_the_contacts.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 6: CIRCUIT BREAKER\n",
+"\n",
+"// EXAMPLE : 6.5 :\n",
+"// Page number 565\n",
+"clear ; clc ; close ; // Clear the work space and console\n",
+"\n",
+"// Given data\n",
+"kV = 132.0 // Voltage(kV)\n",
+"C = 0.01*10**-6 // Phase to ground capacitance(F)\n",
+"L = 6.0 // Inductance(H)\n",
+"i = 5.0 // Magnetizing current(A)\n",
+"\n",
+"// Calculations\n",
+"V_pros = i*(L/C)**0.5/1000 // Prospective value of voltage(kV)\n",
+"R = 1.0/2*(L/C)**0.5/1000 // Resistance to be used across the contacts to eliminate the restriking voltage(k-ohm)\n",
+"\n",
+"// Results\n",
+"disp('PART III - EXAMPLE : 6.5 : SOLUTION :-')\n",
+"printf('\nVoltage across the pole of a CB = %.1f kV', V_pros)\n",
+"printf('\nResistance to be used across the contacts to eliminate the restriking voltage, R = %.2f k-ohm\n', R)\n",
+"printf('\nNOTE: ERROR: Unit of final answer R is k-ohm, not ohm as in the textbook solution')"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 32.6: Rated_normal_current_Breaking_current_Making_current_and_Short_time_rating.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 6: CIRCUIT BREAKER\n",
+"\n",
+"// EXAMPLE : 6.6 :\n",
+"// Page number 567\n",
+"clear ; clc ; close ; // Clear the work space and console\n",
+"\n",
+"// Given data\n",
+"I = 1200.0 // Rated normal current(A)\n",
+"MVA = 1500.0 // Rated MVA\n",
+"kV = 33.0 // Voltage(kV)\n",
+"\n",
+"// Calculations\n",
+"I_breaking = MVA/(3**0.5*kV) // Rated symmetrical breaking current(kA)\n",
+"I_making = I_breaking*2.55 // Rated making current(kA)\n",
+"I_short = I_breaking // Short-time rating(kA)\n",
+"\n",
+"// Results\n",
+"disp('PART III - EXAMPLE : 6.6 : SOLUTION :-')\n",
+"printf('\nRated normal current = %.f A', I)\n",
+"printf('\nBreaking current = %.2f kA (rms)', I_breaking)\n",
+"printf('\nMaking current = %.f kA', I_making)\n",
+"printf('\nShort-time rating = %.2f kA for 3 secs', I_short)"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 32.8: EX32_8.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 6: CIRCUIT BREAKER\n",
+"\n",
+"// EXAMPLE : 6.8 :\n",
+"// Page number 569\n",
+"clear ; clc ; close ; // Clear the work space and console\n",
+"\n",
+"// Given data\n",
+"kVA = 7500.0 // Rated kVA\n",
+"X_st = 9.0 // Sub-transient reactance(%)\n",
+"X_t = 15.0 // Transient reactance(%)\n",
+"X_d = 100.0 // Direct-axis reactance(%)\n",
+"kV = 13.8 // Voltage(kV). Assumption\n",
+"\n",
+"// Calculations\n",
+"kVA_base = 7500.0 // Base kVA\n",
+"kVA_sc_sustained = kVA_base/X_d*100 // Sustained S.C kVA\n",
+"I_sc_sustained = kVA_base/(3**0.5*kV) // Sustained S.C current(A). rms\n",
+"I_st = kVA*100/(X_st*3**0.5*kV) // Initial symmetrical rms current in the breaker(A)\n",
+"I_max_dc = 2**0.5*I_st // Maximum possible dc component of the short-circuit(A)\n",
+"I_moment = 1.6*I_st // Momentary current rating of the breaker(A)\n",
+"I_interrupt = 1.1*I_st // Current to be interrupted by the breaker(A)\n",
+"I_kVA = 3**0.5*I_interrupt*kV // Interrupting kVA\n",
+"\n",
+"// Results\n",
+"disp('PART III - EXAMPLE : 6.8 : SOLUTION :-')\n",
+"printf('\nCase(a): Sustained short circuit KVA in the breaker = %.f kVA', kVA_sc_sustained)\n",
+"printf('\n Sustained short circuit current in the breaker = %.1f A (rms)', I_sc_sustained)\n",
+"printf('\nCase(b): Initial symmetrical rms current in the breaker = %.f A (rms)', I_st)\n",
+"printf('\nCase(c): Maximum possible dc component of the short-circuit in the breaker = %.f A', I_max_dc)\n",
+"printf('\nCase(d): Momentary current rating of the breaker = %.f A (rms)', I_moment)\n",
+"printf('\nCase(e): Current to be interrupted by the breaker = %.f A (rms)', I_interrupt)\n",
+"printf('\nCase(f): Interrupting kVA = %.f kVA \n', I_kVA)\n",
+"printf('\nNOTE: Changes in the obtained answer from that of textbook due to more approximation in textbook')"
+ ]
+ }
+],
+"metadata": {
+ "kernelspec": {
+ "display_name": "Scilab",
+ "language": "scilab",
+ "name": "scilab"
+ },
+ "language_info": {
+ "file_extension": ".sce",
+ "help_links": [
+ {
+ "text": "MetaKernel Magics",
+ "url": "https://github.com/calysto/metakernel/blob/master/metakernel/magics/README.md"
+ }
+ ],
+ "mimetype": "text/x-octave",
+ "name": "scilab",
+ "version": "0.7.1"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
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