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{
"metadata": {
"name": "",
"signature": "sha256:f9430cdf3ccbe0455a5081c4e47c887588ff78214ec8703c5bcd6324cca5d35d"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 5 : Single Phase Transformers"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.1 Page No : 5.5"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"# Variables\n",
"kVA = 250.;\t\t\t\t#kVA\n",
"V1 = 11000.;\t\t\t\t#V(Primary voltage)\n",
"V2 = 400.;\t\t\t\t#V(secondary voltage)\n",
"f = 50.;\t\t\t\t#Hz\n",
"N2 = 80.;\t\t\t\t#no. of turns in secondary\n",
"\n",
"# Calculations and Results\n",
"Ifl1 = kVA*1000/V1;\t\t\t\t#A(Full load primay current)\n",
"Ifl2 = kVA*1000/V2;\t\t\t\t#A(Full load secondary current)\n",
"print (\"Part(a)\");\n",
"print \"Full load primary current(A) %.2f\"%Ifl1\n",
"print \"Full load secondary current(A) : %.2f\"%Ifl2\n",
"\n",
"print (\"Part(b)\");\n",
"N1 = N2*V1/V2;\t\t\t\t#no. of turns in secondary\n",
"print \"No. of turns in primary : %.2f\"%N1\n",
"print (\"Part(c)\");\n",
"fi_m = V2/(4.44*N2*f);\t\t\t\t#Wb\n",
"print \"Maximum value of flux(mWb) : %2.f\"%(fi_m*1000)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Part(a)\n",
"Full load primary current(A) 22.73\n",
"Full load secondary current(A) : 625.00\n",
"Part(b)\n",
"No. of turns in primary : 2200.00\n",
"Part(c)\n",
"Maximum value of flux(mWb) : 23\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.2 Page No : 5.6"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\n",
"# Variables\n",
"N1 = 480;\t\t\t\t#no. of turns in primary\n",
"N2 = 90;\t\t\t\t#no. of turns in secondary\n",
"lfp = 1.8;\t\t\t\t#m(length of flux path)\n",
"ag = 0.1;\t\t\t\t#mm(airgap)\n",
"Flux = 1.1;\t\t\t\t#T(flux density)\n",
"MF = 400;\t\t\t\t#A/m(Magnetic flux)\n",
"c_loss = 1.7;\t\t\t\t#W/kg\n",
"f = 50;\t\t\t\t#Hz\n",
"d = 7800;\t\t\t\t#kg/m**3(density of core)\n",
"V = 2200;\t\t\t\t#V(potential difference)\n",
"\n",
"# Calculations and Results\n",
"#Part (a)\n",
"fi_m = V/(4.44*N1*f);\t\t\t\t#Wb\n",
"A = fi_m/Flux;\t\t\t\t#m**2(Cross sectional area)\n",
"print \"(a) Cross sectional area(m**2) : %.2f\"%A\n",
"#Part (b)\n",
"Vnl2 = V*N2/N1;\t\t\t\t#V(2ndary voltage on no load)\n",
"print \"(b) 2ndary voltage on no load(V) : %.f\"%Vnl2\n",
"\n",
"#Part (c)\n",
"Fm1 = MF*lfp;\t\t\t\t#A(Magnetootive force for the core)\n",
"Fm2 = Flux/(4*math.pi*10**-7)*ag*10**-3;\t\t\t\t#A(Magnetootive force for airgap)\n",
"Fm = Fm1+Fm2;\t\t\t\t#A(Total magnetomotive force)\n",
"Imax = Fm/N1;\t\t\t\t#A(maximum value of magnetizing current)\n",
"Iom = Imax/math.sqrt(2);\t\t\t\t#A(rms current)\n",
"v = lfp*A;\t\t\t\t#m**3(Volume of core)\n",
"m = v*d;\t\t\t\t#kg(Mass of core)\n",
"coreLoss = c_loss*m;\t\t\t\t#W(Core Loss)\n",
"Io1 = coreLoss/V;\t\t\t\t#A(Core loss component of curent)\n",
"Io = math.sqrt(Iom**2+Io1**2);\t\t\t\t#A(no load current)\n",
"print \"(c) Primary current on no load(A) : %.2f\"%Io\n",
"\n",
"pf = Io1/Io;\t\t\t\t#lagging pf on no load\n",
"print \"(c) Power factor(lagging) on no load : %.2f\"%pf\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a) Cross sectional area(m**2) : 0.02\n",
"(b) 2ndary voltage on no load(V) : 412\n",
"(c) Primary current on no load(A) : 1.21\n",
"(c) Power factor(lagging) on no load : 0.17\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.3 Page No : 5.8"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"N1 = 1000;\t\t\t\t#no. of turns in primary\n",
"N2 = 200;\t\t\t\t#no. of turns in secondary\n",
"I0 = 3;\t\t\t\t#A\n",
"pf0 = 0.2;\t\t\t\t#lagging power factor\n",
"I2 = 280;\t\t\t\t#A(2ndary current)\n",
"pf2 = 0.8;\t\t\t\t#lagging power factor\n",
"\n",
"# Calculations and Results\n",
"I2dash = I2*N2/N1;\t\t\t\t#A\n",
"cosfi0 = pf0;cosfi2 = pf2;sinfi0 = math.sqrt(1-cosfi0**2);sinfi2 = math.sqrt(1-cosfi2**2);\n",
"I1_cosfi1 = I2dash*cosfi2+I0*cosfi0;\t\t\t\t#A\n",
"I1_sinfi1 = I2dash*sinfi2+I0*sinfi0;\t\t\t\t#A\n",
"I1 = math.sqrt(I1_cosfi1**2+I1_sinfi1**2);\t\t\t\t#A\n",
"print \"Primary current(A) : %.1f\"%I1\n",
"\n",
"fi1 = math.degrees(math.atan(I1_sinfi1/I1_cosfi1));\t\t\t\t#degree\n",
"pf1 = math.cos(math.radians(fi1));\t\t\t\t#lagging\n",
"print \"Primary power factor(lagging) : %.2f\"%pf1\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Primary current(A) : 58.3\n",
"Primary power factor(lagging) : 0.78\n"
]
}
],
"prompt_number": 9
}
],
"metadata": {}
}
]
}
|
