{
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"name": ""
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"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"CHAPTER 3: DC DYNAMO VOLTAGE RELATIONS-DC GENERATORS"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.1, Page number 69"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"kW = 150.0 #Power rating of Shunt generator(kW)\n",
"V_1 = 250.0 #Voltage rating of Shunt generator(V)\n",
"V_a = V_1 #Voltage rating of Shunt generator(V)\n",
"R_f = 50.0 #Field resistance(ohm)\n",
"R_a = 0.05 #Armature resistance(ohm)\n",
"\n",
"#Calculation\n",
"I_1 = kW*1000/V_1 #Full-load line current flowing to the load(A)\n",
"I_f = V_1/R_f #Field current(A)\n",
"I_a = I_f+I_1 #Armature current(A)\n",
"E_g = V_a+(I_a*R_a) #Full load generated voltage(V)\n",
"\n",
"#Result\n",
"print('Case(a): Full-load line current flowing to the load , I_1 = %.f A' %I_1)\n",
"print('Case(b): Field current , I_f = %.f A' %I_f)\n",
"print('Case(c): Armature current , I_a = %.f A' %I_a)\n",
"print('Case(d): Full-load generated voltage , E_g = %.2f A' %E_g)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Case(a): Full-load line current flowing to the load , I_1 = 600 A\n",
"Case(b): Field current , I_f = 5 A\n",
"Case(c): Armature current , I_a = 605 A\n",
"Case(d): Full-load generated voltage , E_g = 280.25 A\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.2, Page number 72"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"kW =100.0 #Power rating of the generator(kW)\n",
"V_1 = 500.0 #Voltage rating of hte generator(V)\n",
"R_a = 0.03 #Armature resistance(ohm)\n",
"R_f = 125.0 #Shunt field resistance(ohm)\n",
"R_s = 0.01 #Series field resistance(ohm)\n",
"I_d = 54.0 #Diverter current(A)\n",
"\n",
"#Calculation\n",
"#Case(a)\n",
"I_1 = kW*1000/V_1 #Full-load line current flowing to the load(A)\n",
"I_f = V_1/R_f #Shunt Field current(A)\n",
"I_a = I_f+I_1 #Armature current(A)\n",
"I_s = I_a-I_d #Series Field current(A)\n",
"R_d = I_s*R_s/I_d #Diverter resistance(ohm)\n",
"#Case(b)\n",
"E_g = V_1+I_a*R_a+I_s*R_s #Generated voltage at full load(V)\n",
"\n",
"#Result\n",
"print('Case(a): Diverter resistance at full load , R_d = %.4f \u03a9' %R_d)\n",
"print('Case(b): Generated voltage at full load , E_g = %.2f V' %E_g)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Case(a): Diverter resistance at full load , R_d = 0.0278 \u03a9\n",
"Case(b): Generated voltage at full load , E_g = 507.62 V\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.3, Page number 75"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"E_orig = 150.0 #Armature voltage of the generator(V)\n",
"S_orig = 1800.0 #Speed of the generator(rpm)\n",
"S_final_a =2000.0 #Increased Speed of the generator(rpm)\n",
"S_final_b =1600.0 #Increased Speed of the generator(rpm)\n",
"\n",
"#Calculation\n",
"E_final_a = E_orig*(S_final_a/S_orig) #No-load voltage of the generator(V)\n",
"E_final_b = E_orig*(S_final_b/S_orig) #No-load voltage of the generator(V)\n",
"\n",
"#Result\n",
"print('Case(a): No-load voltage of the separately excited generator , E_final = %.2f V' %E_final_a)\n",
"print('Case(b): No-load voltage of the separately excited generator , E_final = %.2f V' %E_final_b)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Case(a): No-load voltage of the separately excited generator , E_final = 166.67 V\n",
"Case(b): No-load voltage of the separately excited generator , E_final = 133.33 V\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.4, Page number 75"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"S_final = 1200.0 #Speed of the generator(rpm)\n",
"E_orig_a = 64.3 #Armature voltage of the generator(V) for case a\n",
"S_orig_a = 1205.0 #Varied Speed of the generator(rpm)\n",
"E_orig_b = 82.9 #Armature voltage of the generator(V) for case b\n",
"S_orig_b = 1194.0 #Varied Speed of the generator(rpm)\n",
"E_orig_c = 162.3 #Armature voltage of the generator(V) for case c\n",
"S_orig_c = 1202.0 #Varied Speed of the generator(rpm)\n",
"\n",
"#Calculation\n",
"E_1 = E_orig_a*(S_final/S_orig_a) #No-load voltage of the generator(V)\n",
"E_2 = E_orig_b*(S_final/S_orig_b) #No-load voltage of the generator(V)\n",
"E_3 = E_orig_c*(S_final/S_orig_c) #No-load voltage of the generator(V)\n",
"\n",
"#Result\n",
"print('Case(a): No-load voltage of the generator , E_1 = %.1f V at %.f rpm' %(E_1,S_final))\n",
"print('Case(b): No-load voltage of the generator , E_2 = %.1f V at %.f rpm' %(E_2,S_final))\n",
"print('Case(c): No-load voltage of the generator , E_3 = %.1f V at %.f rpm' %(E_3,S_final))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Case(a): No-load voltage of the generator , E_1 = 64.0 V at 1200 rpm\n",
"Case(b): No-load voltage of the generator , E_2 = 83.3 V at 1200 rpm\n",
"Case(c): No-load voltage of the generator , E_3 = 162.0 V at 1200 rpm\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.5, Page number 82"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"V = 125.0 #Rated voltage of the shunt generator(V)\n",
"R_a = 0.15 #Armature resistance(ohm)\n",
"V_a = 0 #Terminal voltage across the load(V)\n",
"I_l = 96.0 #Load current(A)\n",
"I_f = 4.0 #Field current in A\n",
"\n",
"#Calculation\n",
"I_a = I_f+I_l #Armature current(A)\n",
"E_g = V_a+I_a*R_a #Voltage generated in the armature(V)\n",
"\n",
"#Result\n",
"print('Voltage generated in the armature , E_g = %.f V' %E_g)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Voltage generated in the armature , E_g = 15 V\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.6, Page number 84"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"V_nl = 135.0 #No-load voltage of the shunt generator(V)\n",
"V_fl = 125.0 #Full-load voltage of the shunt generator(V)\n",
"\n",
"#Calculation\n",
"VR = (V_nl-V_fl)/V_fl*100 #Voltage regulation(%)\n",
"\n",
"#Result\n",
"print('Voltage regulation , VR = %.f percent' %VR)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Voltage regulation , VR = 8 percent\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.7, Page number 84"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"VR = 0.105 #Voltage regulation\n",
"V_fl = 250.0 #Full-load voltage of the shunt generator(V)\n",
"\n",
"#Calculation\n",
"V_nl = V_fl+(V_fl*VR) #No-load voltage of the generator(V)\n",
"\n",
"#Result\n",
"print('No-load voltage of the generator , V_nl = %.1f V' %V_nl)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"No-load voltage of the generator , V_nl = 276.2 V\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.8, Page number 88"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"N_f = 1000.0 #Shunt field winding(turns/pole)\n",
"N_s = 4.0 #Series field winding(turns/pole)\n",
"I_f = 0.2 #Field current(A)\n",
"I_a = 80.0 #Full-load armature current(A)\n",
"R_s =0.05 #Series field resistance(ohm)\n",
"\n",
"#Calculation\n",
"I_s_N_s = I_f*N_f #Series field ampere-turns\n",
"I_s =(I_s_N_s)/N_s #Desired current in the series field required to produce voltage rise(A)\n",
"I_d = I_a-I_s #Diverter current(A)\n",
"R_d = (I_s*R_s)/I_d #Diverter resistance(ohm)\n",
"\n",
"#Result\n",
"print('Case(a): Number of series field ampere-turns required for flat-compound operation , I_sN_s = %.f At' %I_s_N_s)\n",
"print('Case(b): Diverter resistance required for flat-compound operation , R_d = %.4f \u03a9' %R_d)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Case(a): Number of series field ampere-turns required for flat-compound operation , I_sN_s = 200 At\n",
"Case(b): Diverter resistance required for flat-compound operation , R_d = 0.0833 \u03a9\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.9, Page number 89"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"kW = 60.0 #Power rating of the generator(kW)\n",
"V = 240.0 #Voltage rating of the generator(V)\n",
"I_f = 3.0 #Increase in the field current(A)\n",
"OC_V = 275.0 #Over-compounded Voltage(V)\n",
"I_l = 250.0 #Rated load current(A)\n",
"N_f = 200.0 #Number of turns per pole in the shunt field winding \n",
"N_s = 5.0 #Number of turns per pole in the series field winding \n",
"R_f = 240.0 #Shunt field resistance(ohm)\n",
"R_s = 0.005 #Series field resistance(ohm)\n",
"\n",
"#Calculation\n",
"#Case(a)\n",
"I_s_N_s = I_f * N_f #Series field ampere-turns\n",
"I_s = (I_s_N_s)/N_s #Desired current in the series field required to produce voltage rise(A)\n",
"I_d = I_l-I_s #Diverter current(A)\n",
"R_d = (I_s*R_s)/I_d #Diverter resistance(ohm)\n",
"#Case(b)\n",
"NL_MMF = (V/R_f)*N_f #No-load MMF(At/pole)\n",
"I_f_N_f = NL_MMF\n",
"FL_MMF = I_f_N_f+I_s_N_s #Full-load MMF(At/pole)\n",
"\n",
"#Result\n",
"print('Case(a): Required diverter resistance , R_d = %.5f \u03a9' %R_d)\n",
"print('Case(b): Total air-gap MMF per pole at no load , No-load MMF = %.f At/pole' %NL_MMF)\n",
"print(' Total air-gap MMF per pole at full load , Full-load MMF = %.f At/pole' %FL_MMF)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Case(a): Required diverter resistance , R_d = 0.00462 \u03a9\n",
"Case(b): Total air-gap MMF per pole at no load , No-load MMF = 200 At/pole\n",
" Total air-gap MMF per pole at full load , Full-load MMF = 800 At/pole\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3.10, Page number 93"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"kW= 50.0 #Power rating of the dynamo(kW)\n",
"V = 125.0 #Rated voltage(V)\n",
"S = 1800.0 #Speed of the dynamo(rpm)\n",
"I_f = 20.0 #Exciting field current(A)\n",
"Max_temp_rise = 25.0 #Maximum Temperature rise(degree celsius)\n",
"I_l = 400.0 #Load Current(A)\n",
"\n",
"#Result\n",
"print('Case(a): Since the speed is reduced in half,we must reduce the kW rating in half.Consequently,the 25kW, 900rpm dynamo has the SAME size');\n",
"print('Case(b): Since we have cut the speed in half but maintained the same kW rating, the dynamo has TWICE the size as the original')\n",
"print('Case(c): HALF the size')\n",
"print('Case(d): SAME size')"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Case(a): Since the speed is reduced in half,we must reduce the kW rating in half.Consequently,the 25kW, 900rpm dynamo has the SAME size\n",
"Case(b): Since we have cut the speed in half but maintained the same kW rating, the dynamo has TWICE the size as the original\n",
"Case(c): HALF the size\n",
"Case(d): SAME size\n"
]
}
],
"prompt_number": 1
}
],
"metadata": {}
}
]
}