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{
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{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Chapter 3 : Magnetic Circuits"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 1 : pg 42"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"total ampere-turns required is, (AT)= 2001.15\n"
]
}
],
"source": [
"# Example 3.1;ampere-turns\n",
"#calculate the ampere turns required\n",
"# given :\n",
"from math import pi\n",
"bt=([[2],[2.5],[3.0]])#making equations from Table\n",
"H=([[400],[600],[800]]);#making equations from Tble\n",
"fsl=10**-3;#Flux in Wb\n",
"cal=4*10**-4;#area in m**2\n",
"#calculations \n",
"fdl=fsl/cal;#magnetic field in Tesla\n",
"hl=H[1][0];#AT/m \n",
"pll=0.57;#lenth in meter (path length 2345)\n",
"at2345=pll*hl;#ampere turns\n",
"fcl=2*10**-3;#magnetic field in Wb\n",
"fdcl=fcl/cal;#in Tesla\n",
"hcl=H[0][0];#in AT/m\n",
"lcl=169;#length in mm\n",
"atcl=(lcl*10**-3)*hcl;#ampere turns\n",
"l=1;#length mm\n",
"Hl=((4*pi))*10**-7;#AT/m\n",
"atrg=fcl/Hl;#AT\n",
"tat=at2345+atcl+atrg;#total ampere turns\n",
"#results\n",
"print \"total ampere-turns required is, (AT)=\",round(tat,2)\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 2 : pg 44"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"part (a) Kb and Ke\n",
"Kh is 0.39\n",
"Ke is 0.00424\n",
"part (b) hystresis and eddy current loss \n",
"hysteresis loss at 25 Hz is , (W)= 9.75\n",
"eddy current loss at 25 Hz is ,(W)= 2.65\n",
"hysteresis loss at 50 Hz is ,(W)= 19.5\n",
"eddy current loss at 50 Hz is ,(W)= 10.6\n",
"part (c) hystresis and eddy current loss \n",
"hysteresis loss per kg at 50 Hz is ,(W)= 0.4875\n",
"eddy current loss per kg at 50 Hz is ,(W)= 0.265\n"
]
}
],
"source": [
"# Example 3.2;\n",
"#calculate the Kb,Ke,hystresis and eddy current loss\n",
"import numpy\n",
"# given :\n",
"f1=50.;#frequency in Hz\n",
"f2=25.;#frequency in Hz\n",
"p1=30.1;#power in W\n",
"p2=12.4;#power in W\n",
"#calculations and results\n",
"A=([[f1, f1**2],[f2, f2**2]]);#making equations\n",
"B=([[p1],[p2]]);##making equations\n",
"X=numpy.dot(numpy.linalg.inv(A),B);#calculating parameters\n",
"print \"part (a) Kb and Ke\"\n",
"print \"Kh is \", X[0,0]\n",
"print \"Ke is \",X[1,0]\n",
"h25=X[0,0]*f2;#calculating parameters\n",
"e25=X[1,0]*f2**2;#calculating parameters\n",
"h50=X[0,0]*f1;#calculating parameters\n",
"e50=X[1,0]*f1**2;#calculating parameters\n",
"print \"part (b) hystresis and eddy current loss \"\n",
"print \"hysteresis loss at 25 Hz is , (W)=\",h25\n",
"print \"eddy current loss at 25 Hz is ,(W)=\",e25\n",
"print \"hysteresis loss at 50 Hz is ,(W)=\",h50\n",
"print \"eddy current loss at 50 Hz is ,(W)=\",e50\n",
"W=40;#kg\n",
"h50=X[0,0]*f1;#calculating parameters\n",
"e50=X[1,0]*f1**2;#calculating parameters\n",
"print \"part (c) hystresis and eddy current loss \"\n",
"print \"hysteresis loss per kg at 50 Hz is ,(W)=\",h50/W\n",
"print \"eddy current loss per kg at 50 Hz is ,(W)=\",e50/W\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 3 : pg 46"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"hystersis loss is ,(W/kg)= 6.15\n"
]
}
],
"source": [
"# Example 3.3;\n",
"#Calculate the hystresis loss per Kg\n",
"# given :\n",
"l=10.;#lengh in mm\n",
"atm=200.;#AT/m\n",
"a=4800.;#area in m**2\n",
"#calculations\n",
"loss=atm*(l*10**-2)*(a/100);#loss in J/m**3/cycle\n",
"d=7.8*10**3;#kg/m**3\n",
"vikg=1/d;#m**3\n",
"loss1=loss*vikg;#J/cycle\n",
"f=50;#Hz\n",
"tl=loss1*f;#J/s\n",
"#results\n",
"print \"hystersis loss is ,(W/kg)=\",round(tl,2)\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 4 : pg 52"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"ampere turn required is, (AT)= 478.731\n"
]
}
],
"source": [
"# Example 3.4;amper-turns\n",
"#calculate the ampere turn required\n",
"# given :\n",
"from math import sqrt, pi\n",
"r=150.;#length in mm\n",
"t=12.;#torque in N-m\n",
"#calculations\n",
"f=t/(r*10**-3);#force in N\n",
"np=2;#no. of poles\n",
"fp=f/np;#force per pole in N\n",
"A=400.;#area mm**2\n",
"mu=4*pi*10**-7;#\n",
"b=sqrt((fp*2*mu)/(A*10**-6));#magnetic field in Tesla\n",
"H=b/mu;#in AT/m\n",
"tar=2*0.6*10**-3;#length in meter\n",
"atr=H*tar;#AT\n",
"#results\n",
"print \"ampere turn required is, (AT)=\",round(atr,3)\n",
"#answer is wrong in the textbook\n"
]
}
],
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