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{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 15 : Circuit Breakers"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 15.1, Page No 486"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#initialisation of variables\n",
"i=5.0\n",
"L=5*(10**6)\n",
"C=0.01\n",
"\n",
"#Calculations\n",
"e=i*math.sqrt(L/C)\n",
"\n",
"#Results\n",
"print(\"The voltage appearing across the pole of C.B.=%.2f V \" %e)\n",
"R=0.5*math.sqrt(L/C)\n",
"print(\"The value of resistance to be used across contacts, R=%.2f ohms\" %R)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The voltage appearing across the pole of C.B.=111803.40 V \n",
"The value of resistance to be used across contacts, R=11180.34 ohms\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 15.2, Page No 487"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#initialisation of variables\n",
"Vnl=132*math.sqrt(2)/math.sqrt(3) #peak value of peak to neutral voltage(kV)\n",
"Vr1=Vnl*.95 #recovery voltage (kV)\n",
"\n",
"#Calculations\n",
"Vr=102.4*.916 # active recovery voltage(kV)\n",
"Vrmax=2.0*Vr\n",
"fn=16.0*(10**3)\n",
"t=1.0/(2*fn)\n",
"RRRV=Vrmax*(10**-6)/t\n",
"\n",
"#Results\n",
"print(\"Rate of rise of restriking voltage, RRRV = %.0f kV/micro-sec \" %RRRV)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Rate of rise of restriking voltage, RRRV = 6 kV/micro-sec \n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 15.3, Page No 487"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#initialisation of variables\n",
"Vm=132*math.sqrt(2)/math.sqrt(3)\n",
"K1=0.9\n",
"K2=1.5\n",
"K=K1*K2\n",
"sinq=0.92\n",
"\n",
"#Calculations\n",
"Vr=K*Vm*sinq\n",
"fn=16*(10**3)\n",
"RRRV=2*Vr*(10**-6)*fn*2\n",
"\n",
"#Results\n",
"print(\"Average rate of rise of restriking voltage,RRRV=%.3f kV/micro-sec\" %RRRV)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Average rate of rise of restriking voltage,RRRV=8.567 kV/micro-sec\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 15.4 Page No 504"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#initialisation of variables\n",
"In=1500.0\n",
"\n",
"#Calculations\n",
"Ib=2000/(math.sqrt(3.0)*33.0)\n",
"Im=2.55*Ib\n",
"Is=Ib\n",
"\n",
"#Results\n",
"print(\"rated normal current=%.0f amps\" %In)\n",
"print(\"Breaking current=%.2f KA\" %Ib)\n",
"print(\"Making current =%.2f kA\" %Im)\n",
"print(\"Short time rating for 3 sec=%.2f kA \" %Is)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"rated normal current=1500 amps\n",
"Breaking current=34.99 KA\n",
"Making current =89.23 kA\n",
"Short time rating for 3 sec=34.99 kA \n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 15.5, Page No 504"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#initialisation of variables\n",
"MVA=10.0\n",
"Is=MVA*1000/(math.sqrt(3)*13.8)\n",
"print(\"(i)sustained short circuit current in the breaker =%.0f amps\" %Is)\n",
"MVA1=100.0\n",
"Isc=MVA1*1000.0/(math.sqrt(3)*13.8)\n",
"\n",
"#Calculations\n",
"print(\"(ii)initial symmetrical r.m.s current in the breaker r.m.s=%.0f amps\" %Isc)\n",
"Im=math.sqrt(2)*Isc\n",
"print(\"(iii)maximum possible d.c component of the short circuit current in the breaker =%.0f amps\" %Im)\n",
"Im2=1.6*Isc\n",
"print(\"(iv)momentary current rating of the breaker=%.0f amps\" %Im2)\n",
"Ib=1.2*Isc\n",
"print(\"(v)the current to be interrupted by the breaker =%.0f amps\" %Ib)\n",
"KVA=math.sqrt(3)*13.8*5016\n",
"\n",
"#Results\n",
"print(\"(vi)the interupting =%.0f KVA\"%KVA)\n",
"#Answers don't match due to difference in rounding off of digits"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(i)sustained short circuit current in the breaker =418 amps\n",
"(ii)initial symmetrical r.m.s current in the breaker r.m.s=4184 amps\n",
"(iii)maximum possible d.c component of the short circuit current in the breaker =5917 amps\n",
"(iv)momentary current rating of the breaker=6694 amps\n",
"(v)the current to be interrupted by the breaker =5020 amps\n",
"(vi)the interupting =119894 KVA\n"
]
}
],
"prompt_number": 5
}
],
"metadata": {}
}
]
}
|
