1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
|
{
"metadata": {
"name": "",
"signature": "sha256:a058a43eb8f17e03501b9b96349ed2d08d5db7b72234021ac10c6272f4188cf4"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 12: Polyphase System"
]
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 12.1: page 248:"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"from __future__ import division\n",
"import math\n",
"\n",
"#given data:\n",
"L=30 #load in kW\n",
"pf=0.8#power factor\n",
"Vl=250#line voltage in volts\n",
"\n",
"#calculations:\n",
"I=((L*10**3)/(Vl*pf*math.sqrt(3)))#line current in ampers\n",
"Ip1=I # in star connection\n",
"Ip2=I/(math.sqrt(3))#phase current\n",
"Il=math.sqrt(3)*Ip2#line current in amperes\n",
"\n",
"#Results\n",
"print \"(a)line current (star connection) in amperes is\",round(I,2)\n",
"print \"phase current (start connection) in amperes is\",round(Ip1,2)\n",
"print \"(b)phase current in ampere is\",round(Ip2,2)\n",
"print \"line current (delta connection ) in amperes is\",round(Il,2)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a)line current (star connection) in amperes is 86.6\n",
"phase current (start connection) in amperes is 86.6\n",
"(b)phase current in ampere is 50.0\n",
"line current (delta connection ) in amperes is 86.6\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 12.2: page 248:"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"from __future__ import division\n",
"import math\n",
"\n",
"#given data:\n",
"R=11.88#coil resistance in ohms\n",
"L=0.07#inductance in henry\n",
"f=50 # in hertz\n",
"pf=0.48#power factor\n",
"Vl=433#line voltage in volts\n",
"\n",
"#calculations:\n",
"Vp1= Vl/(math.sqrt(3))#phase voltage\n",
"Xl1=(2*math.pi*f*L)#in ohms\n",
"Zb1=math.sqrt(R**2+Xl1**2)# in ohms\n",
"Ie1=Vp1/Zb1#current in each winding in amperes\n",
"Il1=Ie1#line current in amperes\n",
"W1=math.sqrt(3)*Vl*Il1*pf#power in watts\n",
"\n",
"Vp2= Vl#phase voltage\n",
"Xl2=(2*math.pi*f*L)#in ohms\n",
"Zb2=math.sqrt(R**2+Xl2**2)# in ohms\n",
"Ie2=Vp2/Zb2#current in each winding in amperes\n",
"Il2=math.sqrt(3)*Ie2#line current in amperes\n",
"W2=math.sqrt(3)*Vl*Il2*pf#power in watts\n",
"\n",
"#Results\n",
"print \"(a)line current in ampere is\",round(Il1)\n",
"print \"power taken in connection in kW is\",round(W1*10**-3,1)\n",
"print \"(b)line current in ampere is\",round(Il2)\n",
"print \"power taken in connection in kW is\",round(W2*10**-3,1)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a)line current in ampere is 10.0\n",
"power taken in connection in kW is 3.6\n",
"(b)line current in ampere is 30.0\n",
"power taken in connection in kW is 10.8\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 12.3: page 250:"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"from __future__ import division\n",
"\n",
"#given data:\n",
"Vl=1100#line voltage in volts\n",
"n=99 #motor efficiency in percentage\n",
"pf= 0.8#power factor\n",
"\n",
"#calculations:\n",
"Mo=n*735.5#output of the motor\n",
"Mi=(Mo*100)/75# INPUT OF THE MOTOR IN WATTS\n",
"Il=(Mi)/(math.sqrt(3)*Vl*pf)#line current in amperes\n",
"Ip=Il/(math.sqrt(3))#phase current in amperes\n",
"Ipm=Il#phase curent of the motor\n",
"Ac1=Ip*pf#active component of phase current in the motor\n",
"Rc1=Ip*(math.sqrt(1-pf**2))#reactive component of phase current of motor\n",
"Ac2=Ipm*pf#active component of phase current in the generator\n",
"Rc2=Ipm*(math.sqrt(1-pf**2))#reactive component of phase current of generator\n",
"#Results\n",
"print \"(a)phase current of motor in amperes is\",round(Ip,2)\n",
"print \"active component of phase current in the motor in amperes\",round(Ac1,2)\n",
"print \"reactive component of phase current in the motor in amperes\",round(Rc1,2)\n",
"print \"(b)phase current of generator in amperes is\",round(Ipm,2)\n",
"print \"active component of phase current in the generator in amperes\",round(Ac2,3)\n",
"print \"reactive component of phase current in the generator in amperes\",round(Rc2,3)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a)phase current of motor in amperes is 36.77\n",
"active component of phase current in the motor in amperes 29.42\n",
"reactive component of phase current in the motor in amperes 22.06\n",
"(b)phase current of generator in amperes is 63.7\n",
"active component of phase current in the generator in amperes 50.957\n",
"reactive component of phase current in the generator in amperes 38.218\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 12.4: Page 253:"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"from __future__ import division\n",
"import math\n",
"\n",
"#given data:\n",
"ni=74.6#efficiency\n",
"Mo=40#HP OF MOTOR\n",
"tw=40#total in kW\n",
"pf=0.8#power factor\n",
"\n",
"#calculations:\n",
"mo=Mo*ni#output of motor in watts\n",
"mi=(mo*100)/(ni*1000)#input of motor in kW\n",
"theta=math.acos(pf)#in degree\n",
"v=math.tan(theta)#\n",
"dw=(v*tw)/(3**0.5)#\n",
"w1=(tw+dw)/2#FIRST READING IN kW\n",
"w2=tw-w1#second reading in kW\n",
"\n",
"#Results\n",
"print \"first reading in kW is\",round(w1,2)\n",
"print \"second reading in kW is\",round(w2,2) "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"first reading in kW is 28.66\n",
"second reading in kW is 11.34\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 12.5: page 253:"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"from __future__ import division\n",
"import math\n",
"\n",
"#given data:\n",
"w1=4.5#first reading in kW\n",
"w2=3 #second reading in kW , this value is given wrong in question\n",
"\n",
"#calculations:\n",
"tw1=w1+w2#in kW\n",
"dw1=w1-w2#in kW\n",
"pfa1=math.atan(math.sqrt(3)*(dw1/tw1));\n",
"pf1=math.cos(pfa1)#//power factor when both the eadings are positive\n",
"\n",
"tw2=w1-w2#in kW\n",
"dw2=w1+w2#in kW\n",
"pfa2=math.atan(math.sqrt(3)*(dw2/tw2));\n",
"pf2=math.cos(pfa2)#//power factor when second reading is obtained by reversing the connection\n",
"#Results\n",
"print \"(a)power factor when both the readings are positive\", round(pf1,3)\n",
"print \"(b)power factor when second reading is obtained by reversing the connections \",round(pf2,3) "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a)power factor when both the readings are positive 0.945\n",
"(b)power factor when second reading is obtained by reversing the connections 0.115\n"
]
}
],
"prompt_number": 5
}
],
"metadata": {}
}
]
}
|
