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+{
+ "metadata": {
+ "name": "",
+ "signature": "sha256:0e3f32e542105b85338ffef953c9f9ed43138aa30c5d9cb997a0731312a71a64"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+ {
+ "cells": [
+ {
+ "cell_type": "heading",
+ "level": 1,
+ "metadata": {},
+ "source": [
+ "Chapter 2: Induction Motors"
+ ]
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.1, Page 130"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "P=2;#no. of poles\n",
+ "f=60;#in Hz\n",
+ "N=3460.;#in rpm\n",
+ "\n",
+ "#Calculations\n",
+ "Ns=120*f/P;#in rpm\n",
+ "Slip=Ns-N;#in rpm\n",
+ "PercentageSlip=((Ns-N)/Ns)*100;#in %\n",
+ "\n",
+ "#Results\n",
+ "print \"Synchronous speed in rpm : \",Ns;\n",
+ "print \"Percentage Slip : \",round(PercentageSlip,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Synchronous speed in rpm : 3600\n",
+ "Percentage Slip : 3.89\n"
+ ]
+ }
+ ],
+ "prompt_number": 124
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.2, Page 131"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "P=8.;#no. of poles\n",
+ "f=50.;#in Hz\n",
+ "N=700.;#in rpm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "#Part (a) :\n",
+ "Ns=120*f/P;#in rpm\n",
+ "print \"Synchronous speed in rpm : \",Ns;\n",
+ "#Part (b) :\n",
+ "S=(Ns-N)*100/Ns;#in %\n",
+ "print \"Slip(in %) : \",round(S,2);\n",
+ "#Part (c) :\n",
+ "#At the time of stsrt S=1;\n",
+ "fdash=f;#in Hz\n",
+ "print \"Rotor frequeny at the time of starting(in Hz) : \",fdash;\n",
+ "#Part (d) :\n",
+ "fdash=(S/100)*f;#in Hz\n",
+ "print \"Rotor frequeny at the given speed(in Hz) : \",round(fdash,1);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Synchronous speed in rpm : 750.0\n",
+ "Slip(in %) : 6.67\n",
+ "Rotor frequeny at the time of starting(in Hz) : 50.0\n",
+ "Rotor frequeny at the given speed(in Hz) : 3.3\n"
+ ]
+ }
+ ],
+ "prompt_number": 125
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.3, Page 131"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "P=10;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "N=600;#in rpm\n",
+ "Nr=1440;#in rpm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "f=P*N/120;#in Hz\n",
+ "#When P=2\n",
+ "P=2;#no. of poles\n",
+ "Ns=120*f/P;#in rpm\n",
+ "#When P=4\n",
+ "P=4;#no. of poles\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-Nr)*100/Ns;#Slip in %\n",
+ "print \"Percentage Slip(in %) : \",(S);\n",
+ "print \"No. of poles : \",(S);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Percentage Slip(in %) : 4\n",
+ "No. of poles : 4\n"
+ ]
+ }
+ ],
+ "prompt_number": 126
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.4, Page 132"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "P=8;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "fr=1.5;#in Hz\n",
+ "\n",
+ "#Calculations\n",
+ "#Formula : fr=S*f\n",
+ "S=fr/f;#slip(unitless)\n",
+ "Ns=120*f/P;#in rpm\n",
+ "#Formula : S=(Ns-Nr)/Ns\n",
+ "Nr=Ns-S*Ns;#in rpm\n",
+ "\n",
+ "#Results\n",
+ "print \"Motor running speed in rpm : \",round(Nr);\n",
+ "print \"Slip(in %):\",(S*100);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Motor running speed in rpm : 728.0\n",
+ "Slip(in %): 3.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 8
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.5, Page 133"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "P=2;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "S=4.;#in %\n",
+ "\n",
+ "#Calculations&Results\n",
+ "#Part (i) : \n",
+ "Ns=f/P;#in rps\n",
+ "Ns=Ns*60;#in rpm\n",
+ "print \"Synchronous speed in rpm : \",Ns;\n",
+ "#Part (ii) :\n",
+ "print \"Slip = \",(S),\"% or \",(S/100);\n",
+ "#Part (iii) :\n",
+ "N=Ns*(1-S/100);#in rpm\n",
+ "print \"Actual speed in rpm :\",N;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Synchronous speed in rpm : 1500\n",
+ "Slip = 4.0 % or 0.04\n",
+ "Actual speed in rpm : 1440.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 10
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.6, Page 133"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "P=4;#no. of poles\n",
+ "f1=50;#in Hz\n",
+ "fdash=1.5;#in Hz\n",
+ "\n",
+ "#Calculations\n",
+ "S=fdash/f1;#unitless\n",
+ "print \"Slip : \",S;\n",
+ "Ns=120*f1/P;#in rpm\n",
+ "N=Ns*(1-S);#in rpm\n",
+ "\n",
+ "#Result\n",
+ "print \"Speed of motor in rpm :\",N;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.03\n",
+ "Speed of motor in rpm : 1455.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 11
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.7, Page 138"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "N=1440;#in rpm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "f=50;#in Hz\n",
+ "print \"For this speed of 1440 rpm the synchronous speed may be either 1500 rpm or 3000 rpm.\";\n",
+ "Ns=1500;#in rpm\n",
+ "P=4;#no. of poles\n",
+ "print \"No. of poles : \",P;\n",
+ "Slip=(Ns-N)*100/Ns;#in %\n",
+ "print Slip,\"Slip(in %) : \",Slip;\n",
+ "speed1=Ns-N;#Speed of rotor flux with respect to rotor\n",
+ "print \"Speed of rotor flux with respect to rotor in rpm : \",speed1;\n",
+ "speed2=(speed1)+N;#Speed of rotor flux with respect to stator\n",
+ "print \"Speed of rotor flux with respect to stator in rpm :\",speed2;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "For this speed of 1440 rpm the synchronous speed may be either 1500 rpm or 3000 rpm.\n",
+ "No. of poles : 4\n",
+ "4 Slip(in %) : 4\n",
+ "Speed of rotor flux with respect to rotor in rpm : 60\n",
+ "Speed of rotor flux with respect to stator in rpm : 1500\n"
+ ]
+ }
+ ],
+ "prompt_number": 12
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.8, Page 140"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos, acos, tan, atan, degrees\n",
+ "\n",
+ "#Given data : \n",
+ "E2=100;#in volt\n",
+ "R2=0.05;#in ohm\n",
+ "X2=0.1;#im ohm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "E2perphase=E2/sqrt(3);#in volt\n",
+ "#part (a) : \n",
+ "S=0.04;#slip\n",
+ "I2=S*E2perphase/sqrt(R2**2+(S*X2)**2);#in Ampere\n",
+ "print \"At 4% slip, Rotor current in Ampere : \",round(I2,2);\n",
+ "fi2=degrees(acos(R2/sqrt(R2**2+(S*X2)**2)));#in degree\n",
+ "print \"At 4% slip, Phase angle between rotor voltage and rotor current in degree :\",round(fi2,2);\n",
+ "#part (b) : \n",
+ "S=1;#slip\n",
+ "I2=S*E2perphase/sqrt(R2**2+(S*X2)**2);#in Ampere\n",
+ "print \"At 100% slip, Rotor current in Ampere : \",round(I2,2);\n",
+ "fi2=degrees(acos(R2/sqrt(R2**2+(S*X2)**2)));#in degree\n",
+ "print \"At 100% slip, Phase angle between rotor voltage and rotor current in degree :\",round(fi2,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "At 4% slip, Rotor current in Ampere : 46.04\n",
+ "At 4% slip, Phase angle between rotor voltage and rotor current in degree : 4.57\n",
+ "At 100% slip, Rotor current in Ampere : 516.4\n",
+ "At 100% slip, Phase angle between rotor voltage and rotor current in degree : 63.43\n"
+ ]
+ }
+ ],
+ "prompt_number": 2
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.9, Page 141"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import sqrt\n",
+ "\n",
+ "#Given data : \n",
+ "E2=100.;#in volt\n",
+ "R2=0.4;#in ohm\n",
+ "X2=2.25;#im ohm\n",
+ "\n",
+ "#Calculations\n",
+ "E2perphase=E2/sqrt(3);#in volt\n",
+ "S=4.;#in %\n",
+ "E=(S/100)*E2perphase;#rotor induced emf at a slip=4% in volt\n",
+ "Z2=sqrt(R2**2+((S/100)*X2)**2);\n",
+ "I2=E/Z2;#in Ampere\n",
+ "\n",
+ "#Result\n",
+ "print \"Rotor current in Ampere : \",round(I2,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Rotor current in Ampere : 5.63\n"
+ ]
+ }
+ ],
+ "prompt_number": 3
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.10, Page 141"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos\n",
+ "\n",
+ "#Given data : \n",
+ "f=50;#in Hz\n",
+ "R2=0.2;#in ohm\n",
+ "X2=2;#im ohm\n",
+ "E2=60;#in volt\n",
+ "\n",
+ "#Calculations&Results\n",
+ "E2perphase=E2/sqrt(3);#in volt\n",
+ "#case (i) : S=1 \n",
+ "S=1;#unitless\n",
+ "Z2=sqrt(R2**2+(S*X2)**2);\n",
+ "I2=E2perphase*S/Z2;#in Ampere\n",
+ "print \"At standstill : Rotor current in Ampere : \",round(I2,2);\n",
+ "#case (ii) : S=0.1 \n",
+ "S=0.1;#unitless\n",
+ "Z2=sqrt(R2**2+(S*X2)**2);\n",
+ "I2=E2perphase*S/Z2;#in Ampere\n",
+ "print \"for 10% slip : Rotor current in Ampere : \",round(I2,2);\n",
+ "#case (iii) : S=0.05 \n",
+ "S=0.05;#unitless\n",
+ "Z2=sqrt(R2**2+(S*X2)**2);\n",
+ "I2=E2perphase*S/Z2;#in Ampere\n",
+ "print \"for 5% slip : Rotor current in Ampere : \",round(I2,2);\n",
+ "#case (iv) : S=0.01 \n",
+ "S=0.01;#unitless\n",
+ "Z2=sqrt(R2**2+(S*X2)**2);\n",
+ "I2=E2perphase*S/Z2;#in Ampere\n",
+ "print \"for 1% slip : Rotor current in Ampere : \",round(I2,2);\n",
+ "#Note : Answer in the book is wrong for S=0.05 and S=0.01"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "At standstill : Rotor current in Ampere : 17.23\n",
+ "for 10% slip : Rotor current in Ampere : 12.25\n",
+ "for 5% slip : Rotor current in Ampere : 7.75\n",
+ "for 1% slip : Rotor current in Ampere : 1.72\n"
+ ]
+ }
+ ],
+ "prompt_number": 1
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.11, Page 142"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos\n",
+ "\n",
+ "#Given data : \n",
+ "R2=0.5;#in ohm\n",
+ "X=4.5;#im ohm\n",
+ "E=50;#line voltage in volt\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Eperphase=E/sqrt(3);#in volt\n",
+ "#part (a) : Sliprings are short circuited\n",
+ "Z2=sqrt(R2**2+X**2);#in ohm\n",
+ "I2=Eperphase/Z2;#in Ampere\n",
+ "print \"Sliprings are short circuited, Rotor current in Ampere : \",round(I2,2);\n",
+ "cosfi2=R2/Z2;#unitless\n",
+ "print \"Power factor : \",round(cosfi2,2);\n",
+ "#part (b) : Sliprings are connected \n",
+ "R2=0.4;#in ohm\n",
+ "Z2=sqrt(R2**2+X**2);#in ohm\n",
+ "I2=Eperphase/Z2;#in Ampere\n",
+ "print \"Sliprings are short circuited, Rotor current in Ampere : \",round(I2,2);\n",
+ "cosfi2=R2/Z2;#unitless\n",
+ "print \"Power factor : \",round(cosfi2,2);\n",
+ "#Note : answer of part (a) I2 is not curate in the book."
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Sliprings are short circuited, Rotor current in Ampere : 6.38\n",
+ "Power factor : 0.11\n",
+ "Sliprings are short circuited, Rotor current in Ampere : 6.39\n",
+ "Power factor : 0.09\n"
+ ]
+ }
+ ],
+ "prompt_number": 5
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.12, Page 146"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data : \n",
+ "R2=0.02;#in ohm\n",
+ "X2=0.1;#im ohm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "#let external resistance per phase = r then R2=R2+r ohm\n",
+ "S=1;#slip at starting\n",
+ "print \"Since at start speed is zero and slip is, therefore, unity or R2=X2\";\n",
+ "r=X2-R2;#in ohm\n",
+ "print \"External resistance per phase added to the rotor circuit in ohms : \",r;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Since at start speed is zero and slip is, therefore, unity or R2=X2\n",
+ "External resistance per phase added to the rotor circuit in ohms : 0.08\n"
+ ]
+ }
+ ],
+ "prompt_number": 22
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.13, Page 147"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos\n",
+ "\n",
+ "#Given data : \n",
+ "P=4;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "R2=0.03;#in ohm\n",
+ "X2=0.12;#im ohm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Smax=R2/X2;#unitless\n",
+ "Ns=120*f/P;#in rpm\n",
+ "N=Ns*(1-Smax);#in rpm\n",
+ "print \"Speed corresponding to maximum torque(in rpm) :\",N;\n",
+ "#alfa=(R2+r)/X2\n",
+ "#Ratio of starting torque to max torque=75/100=2*alfa/(alfa^2+1)\n",
+ "#It gives : 3*alfa^2-8*alfa+3=0\n",
+ "#coefficients :\n",
+ "a=3;b=-8;c=3;\n",
+ "alfa1=(-b+sqrt(b**2-4*a*c))/(2*a);alfa2=(-b-sqrt(b**2-4*a*c))/(2*a);\n",
+ "print \"rejecting higher values, alfa = \",round(alfa2,4);\n",
+ "fdash=1.5;#in Hz\n",
+ "r=alfa2*X2-R2;#in ohm;\n",
+ "print \"External rotor resistance per phase(in ohm) : \",round(r,4);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Speed corresponding to maximum torque(in rpm) : 1125.0\n",
+ "rejecting higher values, alfa = 0.4514\n",
+ "External rotor resistance per phase(in ohm) : 0.0242\n"
+ ]
+ }
+ ],
+ "prompt_number": 6
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.14, Page 147"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "P=4;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "R2=0.024;#in ohm\n",
+ "X2=0.6;#in ohm \n",
+ "\n",
+ "#Calculations&Results\n",
+ "Sm=R2/X2;#slip corresponding to max torque\n",
+ "Ns=120*f/P;#in rpm\n",
+ "N=Ns*(1-Sm);#in rpm\n",
+ "print \"Speed corresponding to maximum torque in rpm : \",N;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Speed corresponding to maximum torque in rpm : 1440.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 26
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.15, Page 148"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "P=6;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "Sf=4.;#in %\n",
+ "R2=0.01;#in ohm\n",
+ "X2=0.05;#im \n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ratio=((R2/X2)**2+(Sf/100)**2)/(2*R2*(Sf/100)/X2);#ratio of max torque to full load torque\n",
+ "print \"Maximum torque, Tmax=\",(Ratio),\"Tf\";\n",
+ "Sm=R2/X2;#slip corresponding to max torque\n",
+ "Ns=120*f/P;#in rpm\n",
+ "N=Ns*(1-Sm);#in rpm\n",
+ "print \"Speed corresponding to maximum torque in rpm : \",N;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Maximum torque, Tmax= 2.6 Tf\n",
+ "Speed corresponding to maximum torque in rpm : 800.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 28
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.16, Page 149"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "P=12;#no. of poles\n",
+ "f=50.;#in Hz\n",
+ "R2=0.03;#in ohm\n",
+ "X2=0.5;#im \n",
+ "\n",
+ "#Calculations&Results\n",
+ "S=R2/X2;#unitless\n",
+ "Ns=120*f/P;#in rpm\n",
+ "N=Ns*(1-S);#in rpm\n",
+ "print \"Speed at maximum torque in rpm : \",N;\n",
+ "S=(Ns-495)/Ns;#slip at 495 rpm speed\n",
+ "Ratio=(2*R2*S/X2)/((R2/X2)**2+S**2);#ratio of max torque to full load torque\n",
+ "print \"Ratio of full load torque to max torque(in %) :\",round((Ratio*100),1);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Speed at maximum torque in rpm : 470.0\n",
+ "Ratio of full load torque to max torque(in %) : 32.4\n"
+ ]
+ }
+ ],
+ "prompt_number": 142
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.17, Page 149"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos\n",
+ "\n",
+ "#Given data :\n",
+ "P=12;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "R2=0.5;#in ohm\n",
+ "N=475.;#in rpm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-N)/Ns;#unitless\n",
+ "X2=R2/S;#in ohm\n",
+ "#\"At maximum torque, Tmax is proportional to 1/2*X2 or 1/20\";\n",
+ "# \"Ts is proportional to (R2+R)/((R2+R)^2+X2^2)\";\n",
+ "# \"Also, Ts is proportional to 1(20*3)\";\n",
+ "# \"Equating the two eqn we have : (0.5*R)/(R2+R)^2+X2^2\";\n",
+ "#R^2-59R+70.25=0 : \n",
+ "#coefficients :\n",
+ "a=1;b=-59;c=70.25;\n",
+ "R=(-b-sqrt(b**2-4*a*c))/(2*a);\n",
+ "print \"Resistance R to be inserted in series (in ohm) :\",round(R,1);\n",
+ "#Note : answer in the book is wrong."
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Resistance R to be inserted in series (in ohm) : 1.2\n"
+ ]
+ }
+ ],
+ "prompt_number": 7
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.18, Page 150"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "P=4;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "R2=0.04;#in ohm\n",
+ "N=1200.;#in rpm(speed at max torque)\n",
+ "\n",
+ "#Calculations\n",
+ "Ns=120*f/P;#in rpm(synchronous speed)\n",
+ "S=(Ns-N)/Ns;#unitless\n",
+ "X2=R2/S;#in ohm\n",
+ "#Starting torque is the torque devloped when S=1: Tst=K*R2/(R2^2+X2^2)\n",
+ "#Let say, m=R2/(R2^2+X2^2) then Tst=K*m\n",
+ "m=R2/(R2**2+X2**2);#assumed\n",
+ "\n",
+ "#Results\n",
+ "print \"Starting torque, Tst=\",round(m,2),\"k\";\n",
+ "print \"Maximum torque, Tm=K/\",(2*X2);\n",
+ "print \"Thus, Tst in terms of Tm can be expressed as : \";\n",
+ "print \"Tst/Tm=\",(0.96*0.4),\" or Tst=\",(0.96*0.4),\"Tm\";\n",
+ "print \"Therefore, staring torque is \",(0.96*0.4*100),\"% of maximum torque.\";"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Starting torque, Tst= 0.96 k\n",
+ "Maximum torque, Tm=K/ 0.4\n",
+ "Thus, Tst in terms of Tm can be expressed as : \n",
+ "Tst/Tm= 0.384 or Tst= 0.384 Tm\n",
+ "Therefore, staring torque is 38.4 % of maximum torque.\n"
+ ]
+ }
+ ],
+ "prompt_number": 144
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.19, Page 155"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "P=6;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "fr=3.;#in Hz\n",
+ "R2=0.5;#in ohm\n",
+ "N=475;#in rpm\n",
+ "RotorInput=111.9;#in KW\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=fr*100/f;#unitless\n",
+ "print \"% Slip : \",S;\n",
+ "N=Ns*(1-S/100);#in rpm\n",
+ "print \"Speed of motor in rpm : \",N;\n",
+ "RotorCopperLoss=RotorInput*S/100;#in KW\n",
+ "RotorCopperLoss=RotorCopperLoss/3;#in KW/Phase\n",
+ "print \"Rotor Copper Loss per phase(in KW) : \",RotorCopperLoss;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "% Slip : 6.0\n",
+ "Speed of motor in rpm : 940.0\n",
+ "Rotor Copper Loss per phase(in KW) : 2.238\n"
+ ]
+ }
+ ],
+ "prompt_number": 146
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.20, Page 156"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "phase=3.;#no. of phase\n",
+ "Pin_stator=60.;#Power input of stator in KW\n",
+ "TotalStatorLosses=1.;#in KW\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Pin_rotor=Pin_stator-TotalStatorLosses;#Power input of rotor in KW\n",
+ "S=3.;#slip in %\n",
+ "RotorCopperLosses=(S/100)*Pin_rotor;#in KW\n",
+ "RotorCopperLosses=RotorCopperLosses/phase;#in KW per phase\n",
+ "print \"Rotor Copper Losses per phase(in watts) : \",(RotorCopperLosses*10**3);\n",
+ "TotalMechPowerDev=Pin_rotor*(1-S/100);#in KW\n",
+ "print \"Total mechanial power developed(in KW) : \",TotalMechPowerDev;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Rotor Copper Losses per phase(in watts) : 590.0\n",
+ "Total mechanial power developed(in KW) : 57.23\n"
+ ]
+ }
+ ],
+ "prompt_number": 40
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.21, Page 156"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "P=6;#no. of poles\n",
+ "S=4.;#slip in %\n",
+ "Output=20;#in KW\n",
+ "\n",
+ "#Calculations&Results\n",
+ "FrictionalLoss=250;#in watts\n",
+ "f=50;#in Hz\n",
+ "Ns=120*f/P;#in rpm\n",
+ "N=Ns-Ns*(S/100);#in rpm\n",
+ "print \"Speed of motor(in rpm) : \",N;\n",
+ "MechPowerDeveloped=Output*10**3+FrictionalLoss;#in Watts\n",
+ "S=S/100;#unitless\n",
+ "RotorCopperLoss=(S/(1-S))*MechPowerDeveloped;#in watts\n",
+ "print \"Rotor Copper Loss(in watts) : \",RotorCopperLoss;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Speed of motor(in rpm) : 960.0\n",
+ "Rotor Copper Loss(in watts) : 843.75\n"
+ ]
+ }
+ ],
+ "prompt_number": 147
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.22, Page 157"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "phase=3;#no. of phase\n",
+ "P=6;#no. of poles\n",
+ "Pin_rotor=80;#Power input of rotor in KW\n",
+ "f=50;#in Hz\n",
+ "fdash=100;#alternations per minute\n",
+ "\n",
+ "#Calculations&Results\n",
+ "fdash=100./60;#in Hz\n",
+ "S=fdash/f;#unitless\n",
+ "print \"Slip : \",round(S,4);\n",
+ "Ns=120*f/P;#synchronous speed in rpm\n",
+ "N=Ns-Ns*S;#in rpm\n",
+ "print \"Rotor Speed(in rpm) : \",round(N);\n",
+ "MechPowerDev=Pin_rotor*(1-S)*10**3/735.5;#in H.P.\n",
+ "print \"Total mechanial power developed(in KW) : \",round(MechPowerDev,2);\n",
+ "RotorCopperLoss=S*Pin_rotor*10**3;#in watts\n",
+ "print \"Rotor Copper Loss(in watts) : \",RotorCopperLoss;\n",
+ "CopperLoss=RotorCopperLoss/phase;#in watts/phase\n",
+ "print \"Copper Loss per phase(in watts) : \",round(CopperLoss);\n",
+ "I2=60;#in Ampere\n",
+ "R2=CopperLoss/I2**2;#in ohm\n",
+ "print \"Rotor resistance per phase(in ohm) : \",round(R2,3);\n",
+ "#Note : Some answers are not accurate in the book."
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.0333\n",
+ "Rotor Speed(in rpm) : 967.0\n",
+ "Total mechanial power developed(in KW) : 105.14\n",
+ "Rotor Copper Loss(in watts) : 2666.66666667\n",
+ "Copper Loss per phase(in watts) : 889.0\n",
+ "Rotor resistance per phase(in ohm) : 0.247\n"
+ ]
+ }
+ ],
+ "prompt_number": 148
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.23, Page 158"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "UsefulOutput=55;#in H.P.\n",
+ "MechLosses=2;#in H.P.\n",
+ "Stator_Losses=13.5;#in KW\n",
+ "\n",
+ "#Calculations&Results\n",
+ "MechPowerDev=UsefulOutput+MechLosses;#in H.P.\n",
+ "MechPowerDev=MechPowerDev*735.5/1000;#in KW\n",
+ "S=50.;#in %\n",
+ "Pin_Rotor=MechPowerDev/(1-S/100);#in KW\n",
+ "RotorCopperLoss=(S/100)*Pin_Rotor;#in KW\n",
+ "print \"Rotor Copper Loss(in KW) : \",round(RotorCopperLoss,2);\n",
+ "Pin_Motor=Pin_Rotor+Stator_Losses;#in KW\n",
+ "Efficiency=UsefulOutput*0.7355/Pin_Motor;#/unitless\n",
+ "print \"Effiiency(in %) :\",round((Efficiency*100),1);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Rotor Copper Loss(in KW) : 41.92\n",
+ "Effiiency(in %) : 41.6\n"
+ ]
+ }
+ ],
+ "prompt_number": 149
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.24, Page 159"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "phase=3;#no. of phase\n",
+ "P=6;#no. of poles\n",
+ "Pin_rotor=80;#Power input of rotor in KW\n",
+ "f=50;#in Hz\n",
+ "fdash=100;#alternations per minute\n",
+ "\n",
+ "#Calculations&Results\n",
+ "fdash=100./60;#in Hz\n",
+ "S=fdash/f;#unitless\n",
+ "print \"Slip : \",round(S,3);\n",
+ "Ns=120*f/P;#synchronous speed in rpm\n",
+ "N=Ns-Ns*S;#in rpm\n",
+ "print \"Rotor Speed(in rpm) : \",round(N);\n",
+ "RotorCopperLoss=S*Pin_rotor*10**3;#in watts\n",
+ "#print \"Rotor Copper Loss(in watts) : \",RotorCopperLoss;\n",
+ "CopperLoss=RotorCopperLoss/phase;#in watts/phase\n",
+ "print \"Copper Loss per phase(in watts) : \",round(CopperLoss);\n",
+ "I2=60;#in Ampere\n",
+ "R2=CopperLoss/I2**2;#in ohm\n",
+ "print \"Rotorresistance per phase(in ohm) : \",round(R2,3);\n",
+ "MechPowerDev=Pin_rotor*(1-S)*10**3/735.5;#in H.P.\n",
+ "print \"Total mechanial power developed(in H.P.) : \",round(MechPowerDev,1);\n",
+ "#Note : Some answers are not accurate in the book."
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.033\n",
+ "Rotor Speed(in rpm) : 967.0\n",
+ "Copper Loss per phase(in watts) : 889.0\n",
+ "Rotorresistance per phase(in ohm) : 0.247\n",
+ "Total mechanial power developed(in H.P.) : 105.1\n"
+ ]
+ }
+ ],
+ "prompt_number": 150
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.25, Page 160"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "Efficiency=0.9;#unitless\n",
+ "Output=50;#in H.P.\n",
+ "\n",
+ "#Calculations\n",
+ "#formula : Efficiency=Output/(Output+Losses) \n",
+ "Losses=((1-Efficiency)/Efficiency)*Output*735.5;#in watts\n",
+ "Losses=round(Losses);#round\n",
+ "#Let, Ststor Cu loss = Rotor Cu los = Iron loss=K\n",
+ "#Mechanical Loss = Iron Loss/3 = K/3\n",
+ "#TotalLosses=k+K+K+K/3\n",
+ "K=Losses*3/10;#in watts\n",
+ "Pin_rotor=Output*735.5+Losses;#in watts\n",
+ "Slip=K/Pin_rotor;#unitless\n",
+ "\n",
+ "#Results\n",
+ "print \"Slip :\",round(Slip,3);\n",
+ "print \"or \",round((Slip*100)),\"%\"; #answer differes due to rouding"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.03\n",
+ "or 3.0 %\n"
+ ]
+ }
+ ],
+ "prompt_number": 154
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.26, Page 160"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "Pin_rotor=20;#Power input of rotor in KW\n",
+ "phase=3;#no. of phase\n",
+ "P=6;#no. of poles\n",
+ "f=50.;#in Hz\n",
+ "N=960;#in rpm(Actual speed of motor)\n",
+ "\n",
+ "#Calculations\n",
+ "Ns=120*f/P;#synchronous speed in rpm\n",
+ "S=(Ns-N)/Ns;#unitless\n",
+ "RotorCuLoss=S*Pin_rotor*10**3;#in watts\n",
+ "RotorCuLoss=RotorCuLoss/phase;#in watts/phase\n",
+ "R2=1./3;#in ohm(Rotor resistance per phase)\n",
+ "I2=sqrt(RotorCuLoss/R2);#in Ampere\n",
+ "\n",
+ "#Result\n",
+ "print \"Motor current per phase(in Ampere) :\",round(I2,1);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Motor current per phase(in Ampere) : 28.3\n"
+ ]
+ }
+ ],
+ "prompt_number": 155
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.27, Page 161"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "V=500;#in volt\n",
+ "Pout_rotor=20;#Power output of rotor in H.P.\n",
+ "phase=3;#no. of phase\n",
+ "P=6;#no. of poles\n",
+ "f=50;#in Hz\n",
+ "N=995.;#in rpm(Actual speed of motor)\n",
+ "cosfi=0.87;#powerfactor(unitless)\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#synchronous speed in rpm\n",
+ "S=(Ns-N)/Ns;#unitless\n",
+ "print \"Slip : \",S;\n",
+ "RotorCuLoss=(S/(1-S))*Pout_rotor*735.5;#in watts\n",
+ "print \"Rotor Cu Loss(in watts) : \",round(RotorCuLoss,2);\n",
+ "Pin_rotor=RotorCuLoss/S;#in watts\n",
+ "print \"Power input to rotor(in KW) :\",round((Pin_rotor/10**3),2);\n",
+ "LineCurrent=Pin_rotor/(sqrt(3)*V*cosfi);#in Ampere\n",
+ "print \"Line Current(in A) :\",round(LineCurrent,2);\n",
+ "RotorFreq=S*f;#in Hz\n",
+ "print \"Rotor Frequency(in Hz) :\",RotorFreq;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.005\n",
+ "Rotor Cu Loss(in watts) : 73.92\n",
+ "Power input to rotor(in KW) : 14.78\n",
+ "Line Current(in A) : 19.62\n",
+ "Rotor Frequency(in Hz) : 0.25\n"
+ ]
+ }
+ ],
+ "prompt_number": 156
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.28, Page 162"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "phase=3;#no. of phase\n",
+ "Efficiency=90;#in %\n",
+ "Speed=480;#in rpm\n",
+ "VL=400;#in volt\n",
+ "IL=75;#in Ampere\n",
+ "cosfi=0.77;#powerfactor(unitless)\n",
+ "d=0.75;#diameter of pulley in meter\n",
+ "\n",
+ "#Calculations\n",
+ "Pin_motor=sqrt(3)*VL*IL*cosfi;#Power input of motor in watts\n",
+ "OutputPower=Pin_motor*Efficiency/100;#in watts\n",
+ "Omega=Speed*2*pi/60;#angular speed in radians/sec\n",
+ "Torque=OutputPower/Omega;#in N-meter\n",
+ "Torque=Torque/9.81;#in Kg-meter\n",
+ "PullOnBelt=Torque/(d/2);#in Kg\n",
+ "\n",
+ "#Result\n",
+ "print \"Pull On Belt(in Kg.) : \",round(PullOnBelt,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Pull On Belt(in Kg.) : 194.74\n"
+ ]
+ }
+ ],
+ "prompt_number": 157
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.29, Page 162"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "#At 3% slip\n",
+ "OutputPower=24;#in KW(At 3% slip)\n",
+ "S=3.;#in %\n",
+ "\n",
+ "#Calculations\n",
+ "Efficiency=(1-S/100);#unitless\n",
+ "InputPower=OutputPower/Efficiency;#in KW\n",
+ "#At 5% slip\n",
+ "S=5;#in %\n",
+ "Efficiency=(1-S/100);#unitless\n",
+ "OutputPower=InputPower*Efficiency;#in KW\n",
+ "\n",
+ "#Result\n",
+ "print \"Mechanical power output at a slip of 5%(in KW) : \",round(OutputPower,1);\n",
+ "#answer differs due to rounding"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Mechanical power output at a slip of 5%(in KW) : 24.7\n"
+ ]
+ }
+ ],
+ "prompt_number": 158
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.30, Page 162"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "#At 50% speed of synchronous speed\n",
+ "S=50.;#in %\n",
+ "UsefulOutput=55;#in H.P.\n",
+ "MechLoss=2;#in H.P.\n",
+ "StatorLoss=13.5;#in KW\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Pout_rotor=UsefulOutput+MechLoss;#in H.P.\n",
+ "Pout_rotor=Pout_rotor*0.7355;#in KW\n",
+ "Efficiency=(1-S/100);#unitless\n",
+ "RotorInputPower=Pout_rotor/Efficiency;#in KW\n",
+ "RotorCuLoss=RotorInputPower-Pout_rotor;#in KW\n",
+ "print \"Cu Loss in the rotor circuit(in KW) :\",round(RotorCuLoss,2);\n",
+ "TotalLosses=StatorLoss+RotorCuLoss+MechLoss*0.7355;#in KW\n",
+ "MotorEfficiency=UsefulOutput*0.7355/(UsefulOutput*0.7355+TotalLosses);\n",
+ "print \"Motor Efficiency(in %) : \",round((MotorEfficiency*100),1);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Cu Loss in the rotor circuit(in KW) : 41.92\n",
+ "Motor Efficiency(in %) : 41.6\n"
+ ]
+ }
+ ],
+ "prompt_number": 159
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.31, Page 163"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos\n",
+ "\n",
+ "#Given data :\n",
+ "P=4;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "N=1440.;#in rpm(Actual speed of motor)\n",
+ "Power_dev=10;#Power developed in H.P.\n",
+ "VL=400;#in volt\n",
+ "cosfi=0.8;#powerfactor(unitless)\n",
+ "f=50;#in Hz\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-N)/Ns;#fractional slip(unitless)\n",
+ "print \"Slip :\",S;\n",
+ "Omega=N*2*pi/60;#angular speed in radians/sec\n",
+ "Torque=Power_dev*735.5/Omega;#in N-meter\n",
+ "Torque=Torque/9.81;#in Kg-meter\n",
+ "print \"Torque(in Kg-meter) :\",round(Torque,2);\n",
+ "RotorCuLoss=(S/(1-S))*Power_dev*735.5;#in watts\n",
+ "print \"Rotor Cu Loss per phase(in watts) : \",round((RotorCuLoss/3),1);\n",
+ "Pin_rotor=RotorCuLoss/S;#in watts\n",
+ "print \"Power input to rotor(in KW) :\",round((Pin_rotor/10**3),2);\n",
+ "LineCurrent=Pin_rotor/(sqrt(3)*VL*cosfi);#in Ampere\n",
+ "print \"Line Current(in A) :\",round(LineCurrent,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.04\n",
+ "Torque(in Kg-meter) : 4.97\n",
+ "Rotor Cu Loss per phase(in watts) : 102.2\n",
+ "Power input to rotor(in KW) : 7.66\n",
+ "Line Current(in A) : 13.82\n"
+ ]
+ }
+ ],
+ "prompt_number": 8
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.32, Page 164"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "VL=440;#in volt\n",
+ "f=50;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "Pin_rotor=80;#in KW\n",
+ "fr=100;#revolutions/min\n",
+ "\n",
+ "#Calculations&Results\n",
+ "fr=100./60;#in Hz\n",
+ "S=fr/f;#slip(unitless)\n",
+ "print \"Slip : \",round(S,3);\n",
+ "Ns=120*f/P;#in rpm\n",
+ "N=Ns*(1-S);#in rpm(Speed of Rotor)\n",
+ "print \"Rotor speed(in rpm) : \",round(N);\n",
+ "RotorCuLoss=S*Pin_rotor*10**3;#in watts\n",
+ "print \"Rotor Cu Loss per phase(in watts) : \",round(RotorCuLoss/phase);\n",
+ "I2=65;#in Ampere\n",
+ "R2=(RotorCuLoss/phase)/I2**2;#in ohm\n",
+ "print \"Rotor resistance per phase(in ohm) : \",round(R2,2);\n",
+ "Pout_rotor=Pin_rotor-RotorCuLoss/10**3;#in KW\n",
+ "print \"Output power of rotor(in H.P.) : \",round((Pout_rotor/0.735),1);\n",
+ "#Note : answers of few part are not accurate in the book."
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.033\n",
+ "Rotor speed(in rpm) : 967.0\n",
+ "Rotor Cu Loss per phase(in watts) : 889.0\n",
+ "Rotor resistance per phase(in ohm) : 0.21\n",
+ "Output power of rotor(in H.P.) : 105.2\n"
+ ]
+ }
+ ],
+ "prompt_number": 161
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.33, Page 165"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "VL=440;#in volt\n",
+ "f=50.;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "Pin_rotor=20;#in KW\n",
+ "N=960.;#in rpm(Speed of Motor)\n",
+ "\n",
+ "#Calculations\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-N)/Ns;#slip(unitless)\n",
+ "RotorCuLoss=S*Pin_rotor*10**3;#in watts\n",
+ "RotorCuLoss=RotorCuLoss/phase;#in watts/phase\n",
+ "R2=1./3;#Rotor Resistance in ohm per phase\n",
+ "I2=sqrt(RotorCuLoss/R2)\n",
+ "\n",
+ "#Result\n",
+ "print \"Motor current per phase(in Ampere) :\",round(I2,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Motor current per phase(in Ampere) : 28.28\n"
+ ]
+ }
+ ],
+ "prompt_number": 162
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.34, Page 166"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos\n",
+ "\n",
+ "#Given data :\n",
+ "VL=500;#in volt\n",
+ "f=50;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "Pout_rotor=20;#in H.P.\n",
+ "cosfi=0.87;#power factor\n",
+ "N=995.;#in rpm(Speed of Motor)\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-N)/Ns;#slip(unitless)\n",
+ "print \"Slip : \",S;\n",
+ "RotorCuLoss=(S/(1-S))*Pout_rotor*735.5;#in watts\n",
+ "print \"Rotor Cu Loss(in watts) :\",round(RotorCuLoss,2);\n",
+ "Pin_rotor=RotorCuLoss/S;#in watts\n",
+ "print \"Power input to rotor(in KW) :\",round((Pin_rotor/10**3),3);\n",
+ "IL=Pin_rotor/(sqrt(3)*VL*cosfi);#in Ampere\n",
+ "print \"Line current (in Ampere) :\",round(IL,2);\n",
+ "Rotorfreq=S*f;#in Hz\n",
+ "print \"Rotor frequency(in Hz) :\",round(Rotorfreq,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.005\n",
+ "Rotor Cu Loss(in watts) : 73.92\n",
+ "Power input to rotor(in KW) : 14.784\n",
+ "Line current (in Ampere) : 19.62\n",
+ "Rotor frequency(in Hz) : 0.25\n"
+ ]
+ }
+ ],
+ "prompt_number": 9
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.35, Page 166"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=4;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "Efficiency=85.;#in %\n",
+ "OutputPower=17.;#in KW\n",
+ "OutputPower=17*10**3;#in watts\n",
+ "StatorLosses=900.;#in watt\n",
+ "MechLosses=1100;#in watt\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Pin=OutputPower/(Efficiency/100);#in watts\n",
+ "#Stator input or rotor input :\n",
+ "Pin_rotor=Pin-StatorLosses;#in watts\n",
+ "P_MechDev=OutputPower+MechLosses;#in watts\n",
+ "RotorCuLosses=Pin_rotor-P_MechDev;#in watts\n",
+ "S=RotorCuLosses/Pin_rotor;#slip(unitless)\n",
+ "print \"Slip :\",round(S,3);\n",
+ "Ns=120*f/P\n",
+ "N=Ns*(1-S);#in rpm(Speed of Motor)\n",
+ "Omega=2*pi*N/60;#angular speed in rad/sec\n",
+ "Torque=P_MechDev/Omega;#in Nm\n",
+ "print \"Torque developed(in Nm) :\",round(Torque,1);\n",
+ "Tm=OutputPower/Omega;#in Nm\n",
+ "Tm=Tm/9.81;#in Kg-meter\n",
+ "print \"Torque at the shaft(in Kg-meter) :\",round(Tm,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.052\n",
+ "Torque developed(in Nm) : 121.6\n",
+ "Torque at the shaft(in Kg-meter) : 11.64\n"
+ ]
+ }
+ ],
+ "prompt_number": 164
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.36, Page 168"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "VL=500;#in volt\n",
+ "f=50;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "Pin_stator=50;#in KW\n",
+ "Statorlosses=2;#in KW\n",
+ "MechLosses=1;#in KW\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Pin_rotor=Pin_stator-Statorlosses;#in KW\n",
+ "S=3.;#in %\n",
+ "RotorI2RLoss=(S/100)*Pin_rotor;#in KW\n",
+ "print \"Rotor I2R Loss(in KW) :\",RotorI2RLoss;\n",
+ "print \"Rotor core loss at 3% slip is very less and can be neglected.\";\n",
+ "Power_dev=Pin_rotor-RotorI2RLoss;#in KW\n",
+ "print \"Power developed by the rotor(in H.P.) : \",round((Power_dev/0.7355),1);\n",
+ "Outputpower=Power_dev-MechLosses;#in KW\n",
+ "Efficiency=Outputpower/Pin_stator;#unitless\n",
+ "print \"Efficiency of the motor(in %) :\",(Efficiency*100);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Rotor I2R Loss(in KW) : 1.44\n",
+ "Rotor core loss at 3% slip is very less and can be neglected.\n",
+ "Power developed by the rotor(in H.P.) : 63.3\n",
+ "Efficiency of the motor(in %) : 91.12\n"
+ ]
+ }
+ ],
+ "prompt_number": 165
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.37, Page 168"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=4;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "MotorOutput=20;#in H.P.\n",
+ "MotorOutput=20*735.5;#in watts\n",
+ "S=4.;#full load slip in %\n",
+ "MechLosses=500;#in watts\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Pdev_rotor=MotorOutput+MechLosses;#in watts\n",
+ "S=S/100;#fractional slip\n",
+ "RotorI2RLoss=(S/(1-S))*Pdev_rotor;#in watts\n",
+ "print \"Rotor I2R Loss(in watts) :\",RotorI2RLoss;\n",
+ "Ns=120*f/P;#in rpm\n",
+ "Nr=Ns-Ns*S;#in rpm\n",
+ "print \"Rotor speed(in rpm) :\",Nr;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Rotor I2R Loss(in watts) : 633.75\n",
+ "Rotor speed(in rpm) : 1440.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 80
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.38, Page 169"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import pi, sqrt, sin, cos\n",
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "R2=0.02;#in ohm\n",
+ "X2=0.1;#in ohm\n",
+ "\n",
+ "#Calculations\n",
+ "S=R2/X2;#slip(unitless)\n",
+ "Ns=120*f/P;#in rpm\n",
+ "Nr=Ns-Ns*S;#in rpm\n",
+ "#At starting S=1\n",
+ "S=1;#slip\n",
+ "#Formula : T=K*S*R2/(R2^2+X2^2)\n",
+ "#Starting torque, Tst=K*R2/(R2^2+S^2*X2^2)\n",
+ "#Maximum torque, Tm=K/(2*X2)\n",
+ "#Tst=(2/3)*Tm : gives a equation\n",
+ "#100*R2^2-30*R2+1=0\n",
+ "a=100;b=-30;c=1;\n",
+ "R21=(-b+sqrt(b**2-4*a*c))/(2*a);#in ohm\n",
+ "R22=(-b-sqrt(b**2-4*a*c))/(2*a);#in ohm\n",
+ "#This R2 is the value of rotor circuit resistance.\n",
+ "RotWinResistance=0.02;#in ohm per phase\n",
+ "Extra_R1=R21-RotWinResistance;#in ohm\n",
+ "Extra_R2=R22-RotWinResistance;#in ohm\n",
+ "\n",
+ "#Result\n",
+ "print \"Extra Resistance(in ohm) : \",round(Extra_R1,3),\" ohm or \",round((Extra_R2),3),\" ohm.\";"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Extra Resistance(in ohm) : 0.242 ohm or 0.018 ohm.\n"
+ ]
+ }
+ ],
+ "prompt_number": 166
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.39, Page 170"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=4;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "MotorShaftOutput=20;#in H.P.\n",
+ "\n",
+ "#Calculations&Results\n",
+ "MotorShaftOutput=20*735.5;#in watts\n",
+ "MechLosses=MotorShaftOutput*2/100;#in watts(2% of the output)\n",
+ "Pdev_rotor=MotorShaftOutput+MechLosses;#in watts\n",
+ "S=3.;#slip in %\n",
+ "S=S/100;#fractional slip\n",
+ "RotorI2RLoss=(S/(1-S))*Pdev_rotor;#in watts\n",
+ "print \"Rotor I2R Loss(in watts) :\",round(RotorI2RLoss);\n",
+ "print \"Rotor iron loss at 3% slip is very small and can be neglected.\";\n",
+ "RotorInput=Pdev_rotor+RotorI2RLoss;#in watts\n",
+ "print \"Rotor Input(in Watts) :\",round(RotorInput,1);\n",
+ "Ns=120*f/P;#in rpm\n",
+ "Nr=Ns-Ns*S;#in rpm\n",
+ "Nr=Nr/60;#in rps\n",
+ "T=MotorShaftOutput/(2*pi*Nr);#in Nm\n",
+ "print \"Output torque(in Nm) : \",round(T,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Rotor I2R Loss(in watts) : 464.0\n",
+ "Rotor iron loss at 3% slip is very small and can be neglected.\n",
+ "Rotor Input(in Watts) : 15468.2\n",
+ "Output torque(in Nm) : 96.54\n"
+ ]
+ }
+ ],
+ "prompt_number": 167
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.40, Page 171"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "VL=500;#in volt\n",
+ "f=50;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "Nr=975.;#in rpm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-Nr)/Ns;#slip\n",
+ "print \"Slip :\",S;\n",
+ "Pin_stator=40;#in KW\n",
+ "StatorLosses=1;#in KW\n",
+ "Pin_rotor=Pin_stator-StatorLosses;#in KW\n",
+ "RotorCuLosses=S*Pin_rotor;#in KW\n",
+ "print \"Rotor Cu Losses(in KW) :\",RotorCuLosses;\n",
+ "RotorOutput=Pin_rotor-RotorCuLosses;#in KW\n",
+ "OutputHP=RotorOutput/0.735;#in H.P.\n",
+ "print \"Output Horse Power : \",round(OutputHP,2);\n",
+ "Efficiency=RotorOutput/Pin_stator;#unitless\n",
+ "print \"Efficiency(in %) :\",round(Efficiency*100);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.025\n",
+ "Rotor Cu Losses(in KW) : 0.975\n",
+ "Output Horse Power : 51.73\n",
+ "Efficiency(in %) : 95.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 168
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.41, Page 172"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "VL=440;#in volt\n",
+ "f=50.;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3.;#no. of phase\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "fr=120;#alternations per minute\n",
+ "fr=fr/60;#in Hz\n",
+ "S=fr/f;#slip\n",
+ "print \"Slip : \",S;\n",
+ "Nr=Ns-S*Ns;#in rpm\n",
+ "print \"Rotor speed(in rpm) :\",Nr;\n",
+ "Rotor_input=80;#in KW\n",
+ "RotorCuLoss=S*Rotor_input;#in KW\n",
+ "print \"Rotor Cu Loss per phase(in watts) :\",round((RotorCuLoss*10**3)/phase);\n",
+ "P_Mechdev=Rotor_input*10**3-RotorCuLoss*10**3;#in watts\n",
+ "P_Mechdev=P_Mechdev/735.5;#in H.P.\n",
+ "print \"Mechanical power devloped(in H.P.) :\",round(P_Mechdev,1);\n",
+ "Ir=60;#in Ampere\n",
+ "R2=(RotorCuLoss*10**3/phase)/Ir**2;#in ohm\n",
+ "print \"Rotor resistance per phase(in ohm) :\",round(R2,3);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Slip : 0.04\n",
+ "Rotor speed(in rpm) : 960.0\n",
+ "Rotor Cu Loss per phase(in watts) : 1067.0\n",
+ "Mechanical power devloped(in H.P.) : 104.4\n",
+ "Rotor resistance per phase(in ohm) : 0.296\n"
+ ]
+ }
+ ],
+ "prompt_number": 169
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.43, Page 175 "
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50.;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "R2=0.2;#rotor resistance per phase in ohm\n",
+ "Nr=960;#in rpm\n",
+ "Nr_dash=600;#in rpm\n",
+ "\n",
+ "#Calculations\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-Nr)/Ns;#slip(unitless)\n",
+ "Sdash=(Ns-Nr_dash)/Ns;#slip(unitless)\n",
+ "#Let the new value of resistance is R2dash=(R+0.2)\n",
+ "R=R2*(Sdash/S)-R2;#Resistance to be added in ohm\n",
+ "\n",
+ "#Result\n",
+ "print \"Resistance to be added(in ohm) : \",R;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Resistance to be added(in ohm) : 1.8\n"
+ ]
+ }
+ ],
+ "prompt_number": 91
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.44, Page 176"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=6;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "RotorIntResistance=0.1;#in ohm per phase\n",
+ "X2=1;#in ohm/phase\n",
+ "\n",
+ "#Calculation\n",
+ "Rext=X2-RotorIntResistance;#in ohm\n",
+ "\n",
+ "#Result\n",
+ "print \"External resistance to be included(in ohm/phase) : \",Rext;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "External resistance to be included(in ohm/phase) : 0.9\n"
+ ]
+ }
+ ],
+ "prompt_number": 92
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.45, Page 176"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50.;#in Hz\n",
+ "P=6.;#no. of poles\n",
+ "phase=3.;#no. of phase\n",
+ "R2=0.2;#rotor resistance per phase in ohm\n",
+ "N1=960.;#Full load speed in rpm\n",
+ "\n",
+ "#Calculations\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S1=(Ns-N1)/Ns;#Full load slip(unitless)\n",
+ "N2=N1*(1-10./100);#New speed in rpm(reduced 10%)\n",
+ "S2=(Ns-N2)/Ns;#New slip(unitless)\n",
+ "#Formula : S=RotorCuLoss/Pin_rotor=3*I2^2*R2/Pin_rotor\n",
+ "#Let the additional resistance is R\n",
+ "R=R2*S2/S1-R2;#Resistance to be added in ohm\n",
+ "\n",
+ "#Result\n",
+ "print \"Additional Rotor Resistance(in ohm) : \",R;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Additional Rotor Resistance(in ohm) : 0.48\n"
+ ]
+ }
+ ],
+ "prompt_number": 97
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.46, Page 180"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "R2inner=0.4;#in ohm\n",
+ "X2inner=2;#in ohm \n",
+ "R2outer=2;#in ohm\n",
+ "X2outer=0.4;#in ohm \n",
+ "#At standstill :\n",
+ "S=1;#unitless\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ratio=(R2outer*S/(R2outer**2+S**2*X2outer**2))/(R2inner*S/(R2inner**2+S**2*X2inner**2));#unitless\n",
+ "print \"Ratio of torque produced by two cages at standstill : \",Ratio;\n",
+ "#At Full load :\n",
+ "S=5;#in %\n",
+ "S=5./100;#fractional\n",
+ "Ratio=(R2outer*S/(R2outer**2+S**2*X2outer**2))/(R2inner*S/(R2inner**2+S**2*X2inner**2));#unitless\n",
+ "print \"Ratio of torque produced by two cages at full load(slip=5%) : \",round(Ratio,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Ratio of torque produced by two cages at standstill : 5.0\n",
+ "Ratio of torque produced by two cages at full load(slip=5%) : 0.21\n"
+ ]
+ }
+ ],
+ "prompt_number": 171
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.47, Page 187"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import sqrt\n",
+ "\n",
+ "#Given data :\n",
+ "Output=10;#in H.P.\n",
+ "Output=Output*735.5;#in watts\n",
+ "cosfi=0.8;#unitless\n",
+ "ETA=0.83;#unitless\n",
+ "ISCbyIFL=3.5;#ratio of SC current to full load current\n",
+ "VL=500;#in volt\n",
+ "\n",
+ "#Calculations\n",
+ "Input=Output/ETA;#in watts\n",
+ "IFL=Input/(sqrt(3)*VL*cosfi);#in Ampere\n",
+ "ISC=IFL*ISCbyIFL;#in Ampere\n",
+ "Is=ISC/3;#in Ampere\n",
+ "\n",
+ "#Result\n",
+ "print \"Strting current(in Ampere) :\",round(Is,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Strting current(in Ampere) : 14.92\n"
+ ]
+ }
+ ],
+ "prompt_number": 10
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.48, Page 187"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "ISCbyIFL=5;#ratio of SC current to full load current\n",
+ "S=0.04;#Full load slip\n",
+ "\n",
+ "#Calculations&Results\n",
+ "#(i) for star delta starter : \n",
+ "print \"for star delta starter : \";\n",
+ "Ratio=(1./3)*(ISCbyIFL)**2*S;#Ratio of starting torque to full load torque\n",
+ "print \"Starting torque is \",round((Ratio*100),2),\"% of full load torque.\";\n",
+ "#(i) for auto transformer starter :\n",
+ "print \"for auto transformer starter : \";\n",
+ "K=50./100;#tappings\n",
+ "Ratio=K**2*(ISCbyIFL)**2*S;#Ratio of starting torque to full load torque\n",
+ "print \"Starting torque is \",(Ratio*100),\"% of full load torque.\";"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "for star delta starter : \n",
+ "Starting torque is 33.33 % of full load torque.\n",
+ "for auto transformer starter : \n",
+ "Starting torque is 25.0 % of full load torque.\n"
+ ]
+ }
+ ],
+ "prompt_number": 173
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.49, Page 188"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "ISCbyIFL=4;#ratio of SC current to full load current\n",
+ "TsBYTf=1./4;#ratio of atarting torque to full load torque\n",
+ "Slip=3;#in %\n",
+ "Slip=3./100;#in fraction\n",
+ "\n",
+ "#Calculations\n",
+ "#Formula : TsBYTf=Percent_Tapping^2*ISCbyIFL^2*Slip\n",
+ "tapping=sqrt(TsBYTf/(Slip*ISCbyIFL**2));#in %\n",
+ "\n",
+ "#Result\n",
+ "print \"Tapping(in %) :\",round((tapping*100),1);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Tapping(in %) : 72.2\n"
+ ]
+ }
+ ],
+ "prompt_number": 174
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.50, Page 189"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "ISCbyIFL=5.;#ratio of SC current to full load current\n",
+ "Slip=5;#in %\n",
+ "Slip=5./100;#in fraction\n",
+ "\n",
+ "#Calculations\n",
+ "#Formula : 3*IFL=K^2*ISC\n",
+ "K=sqrt(1./(ISCbyIFL/3));#unitless\n",
+ "TsBYTfl=K**2*(ISCbyIFL)**2*Slip;#ratio of starting torque to full load torque\n",
+ "\n",
+ "#Result\n",
+ "print \"Starting torque is \",(TsBYTfl*100),\"% of full load torque.\";"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Starting torque is 75.0 % of full load torque.\n"
+ ]
+ }
+ ],
+ "prompt_number": 175
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.51, Page 189"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "print \"Star delta starter :\";\n",
+ "ISCbyIFL=6;#ratio of SC current to full load current\n",
+ "Slip=4;#in %\n",
+ "Slip=4./100;#in fraction\n",
+ "\n",
+ "#Calculations&Results\n",
+ "TsBYTfl=(1./3)*(ISCbyIFL)**2*Slip;#ratio of starting torque to full load torque\n",
+ "print \"Starting torque is \",(TsBYTfl*100),\"% of full load value.\";\n",
+ "print \"For an auto transformer :\";\n",
+ "K=70.70;#in %\n",
+ "K=70.70/100;#in fraction\n",
+ "TsBYTfl=K**2*(ISCbyIFL)**2*Slip;#ratio of starting torque to full load torque\n",
+ "print \"Starting torque is \",round(TsBYTfl*100),\"% of full load torque.\";"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Star delta starter :\n",
+ "Starting torque is 48.0 % of full load value.\n",
+ "For an auto transformer :\n",
+ "Starting torque is 72.0 % of full load torque.\n"
+ ]
+ }
+ ],
+ "prompt_number": 176
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.52, Page 190"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "V=400.;#in volt\n",
+ "S=3.5;#in %\n",
+ "S=3.5/100;#in fraction\n",
+ "VL=92;#in volts\n",
+ "\n",
+ "#Calculations&Results\n",
+ "#ISC=(V/VL)*IFL;#in Ampere\n",
+ "ISCbyIFL=V/VL;#ratio of SC current to full load current\n",
+ "#2*IFL=K^2*ISC imples that 2*IFL=K^2*(V/VL)*IFL\n",
+ "K=sqrt(2./(V/VL));#in fraction\n",
+ "print \"Necessary tapping(in %) :\",round((K*100),1);\n",
+ "TsBYTfl=K**2*(ISCbyIFL)**2*S;#ratio of starting torque to full load torque\n",
+ "print \"Starting torque is \",round((TsBYTfl*100),1),\"% of full load value.\";"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Necessary tapping(in %) : 67.8\n",
+ "Starting torque is 30.4 % of full load value.\n"
+ ]
+ }
+ ],
+ "prompt_number": 179
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.53, Page 190"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "ISCbyIFL=4;#ratio of SC current to full load current\n",
+ "ISbyIFL=2;#ratio of Supply current to full load current\n",
+ "S=2.5;#in %\n",
+ "S=2.5/100;#in fraction\n",
+ "\n",
+ "#Calculations\n",
+ "#Formula : ISbyIFL=(1/K^2)*ISCbyIFL\n",
+ "K=sqrt(ISCbyIFL/ISbyIFL);#in fraction\n",
+ "print \"Auto Transormation ratio :\",round(K,2);\n",
+ "TsBYTfl=(1./K**2)*(ISCbyIFL)**2*S;#ratio of starting torque to full load torque\n",
+ "\n",
+ "#Results\n",
+ "print \"Ratio of starting torque to full load torque :\",TsBYTfl;\n",
+ "print \"or Starting torque is \",(TsBYTfl*100),\"% of full load value.\";"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Auto Transormation ratio : 1.41\n",
+ "Ratio of starting torque to full load torque : 0.2\n",
+ "or Starting torque is 20.0 % of full load value.\n"
+ ]
+ }
+ ],
+ "prompt_number": 180
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.54, Page 191"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "ISCbyIFL=4;#ratio of SC current to full load current\n",
+ "S=3;#in %\n",
+ "S=3./100;#in fraction\n",
+ "TsBYTfl=1./4;#ratio of starting torque to full load torque\n",
+ "\n",
+ "#Calculations\n",
+ "#Formula : TsBYTfl=ISCbyIFL^2*K^2*S\n",
+ "K=sqrt(TsBYTfl/(ISCbyIFL**2*S));#in fraction\n",
+ "\n",
+ "#Result\n",
+ "print \"Auto Transormation ratio(in %) :\",round((K*100),2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Auto Transormation ratio(in %) : 72.17\n"
+ ]
+ }
+ ],
+ "prompt_number": 181
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.55, Page 191"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import sqrt\n",
+ "\n",
+ "#Given data :\n",
+ "Output=3;#in H.P.\n",
+ "Output=3*735.5;#in watts\n",
+ "Efficiency=0.83;#unitless\n",
+ "cosfi=0.8;#power factor\n",
+ "\n",
+ "#Calculations\n",
+ "Vl=500;#in volt\n",
+ "Input=Output/Efficiency;#in watts\n",
+ "#Formula : Input=sqrt(3)*Vl*Il*cosfi\n",
+ "Il=Input/(sqrt(3)*Vl*cosfi);#in Ampere\n",
+ "ISCbyIFL=3.5;#ratio of SC current to full load current\n",
+ "ISC=ISCbyIFL*Il;#in Ampere\n",
+ "LineCurrent=ISC/3;#in Ampere(for star delta starter)\n",
+ "\n",
+ "#Result\n",
+ "print \"Line Current(in Ampere) :\",round(LineCurrent,2);\n",
+ "#Note : Ans in the book is not accurate."
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Line Current(in Ampere) : 4.48\n"
+ ]
+ }
+ ],
+ "prompt_number": 11
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.56, Page 192"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import sqrt\n",
+ "\n",
+ "#Given data :\n",
+ "Output=15;#in H.P.\n",
+ "Output=15*735.5;#in watts\n",
+ "Vl=400;#in volt\n",
+ "ISCat200=40;#in Ampere(at 200 volt)\n",
+ "Efficiency=0.88;#unitless\n",
+ "cosfi=0.85;#power factor\n",
+ "\n",
+ "#Calculations\n",
+ "ISCat400=ISCat200*(400./200);#in Ampere(at 400 volt)\n",
+ "Input=Output/Efficiency;#in watts\n",
+ "Ifl=Input/(sqrt(3)*Vl*cosfi);#in Ampere\n",
+ "#starting line current with star delta starter\n",
+ "Is=ISCat400/3;#in Ampere\n",
+ "Ratio=Is/Ifl;#ratio of starting current to full load current\n",
+ "\n",
+ "#Result\n",
+ "print \"Ratio of line current at starting to full load current :\",round(Ratio,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Ratio of line current at starting to full load current : 1.25\n"
+ ]
+ }
+ ],
+ "prompt_number": 12
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.57, Page 192"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from math import sqrt\n",
+ "\n",
+ "#Given data :\n",
+ "#With star delta starter : \n",
+ "TstBYTfl=0.35;#ratio of starting torque to full load torque\n",
+ "IstBYIfl=1.75;#ratio of starting current to full load current\n",
+ "\n",
+ "#Calculations&Results\n",
+ "ISCBYIs=sqrt(3);#ratio of SC current to starting current\n",
+ "ISCBYIfl=sqrt(3)*IstBYIfl;#ratio of SC current to full load current\n",
+ "#Formula : TstBYTfl=(ISCBYIfl)^2*S\n",
+ "S=TstBYTfl/(ISCBYIfl)**2;#in fraction\n",
+ "print \"Full load Slip : \",round(S,3);\n",
+ "#With auto transformer with winding in delta : \n",
+ "Ip=sqrt(3)*1.750*0.8;#full voltage phase current in Ampere\n",
+ "IlBYIf=4.2;#ratio of Line current to full load current\n",
+ "Ratio=IlBYIf**2*S;#ratio of starting current to full load current\n",
+ "print \"Ratio of line current at starting to full load current :\",round(Ratio,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Full load Slip : 0.038\n",
+ "Ratio of line current at starting to full load current : 0.67\n"
+ ]
+ }
+ ],
+ "prompt_number": 13
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.58, Page 196"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=4;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "R2=0.25;#in ohm per phase\n",
+ "S=2;#in %\n",
+ "S=2./100;#in fraction\n",
+ "\n",
+ "#Calculations\n",
+ "Ns=120*f/P;#in rpm\n",
+ "Nr=Ns-Ns*S;#in rpm\n",
+ "#When speed reduced to 10%\n",
+ "NewSpeed=Nr*90/100;#in rpm\n",
+ "Sdash=(Ns-NewSpeed)/Ns;#in fraction\n",
+ "R2dash=(Sdash/S)*R2;#in ohm per phase\n",
+ "R=R2dash-R2;#in ohm\n",
+ "\n",
+ "#Result\n",
+ "print \"Value of resistance to be added(in ohm) :\",R;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Value of resistance to be added(in ohm) : 1.225\n"
+ ]
+ }
+ ],
+ "prompt_number": 114
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.59, Page 197"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=4;#no. of poles\n",
+ "R2=0.25;#in ohm per phase\n",
+ "N=1440.;#in rpm at full load\n",
+ "NewSpeed=1200;#in rpm\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "S=(Ns-N)/Ns;#in %\n",
+ "NewS=(Ns-NewSpeed)/Ns;#in fraction\n",
+ "S1=S;S2=NewS;#slip new and old\n",
+ "#Torque remaining same : S1/R2=S2/(R2+R)\n",
+ "R=S2*R2/S1-R2;#in ohm\n",
+ "print \"External resistance per phase(in ohm) :\",R; #incorrect answer in textbook\n",
+ "Nr=Ns-Ns*S;#in rpm\n",
+ "#If S1 is taken as 0.03 and S2 as 0.127\n",
+ "S1=0.03;#slip in fraction\n",
+ "S2=0.127;#slip in fraction\n",
+ "R=S2*R2/S1-R2;#in ohm\n",
+ "print \"External resistance per phase(in ohm) :\",round(R,3);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "External resistance per phase(in ohm) : -0.25\n",
+ "External resistance per phase(in ohm) : 0.808\n"
+ ]
+ }
+ ],
+ "prompt_number": 194
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.60, Page 198"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=4;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "S=4;#in %\n",
+ "S=4./100;#in fraction\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "N1=Ns-Ns*S;#in rpm\n",
+ "#When speed reduced to 10%\n",
+ "N2=N1*85/100;#in rpm(NewSpeed)\n",
+ "print \"New speed(in rpm) :\",N2;\n",
+ "#New speed is reduced by 15 %\n",
+ "Sdash=(Ns-N2)/Ns;#in fraction\n",
+ "print \"New Slip : \",Sdash;"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "New speed(in rpm) : 1224.0\n",
+ "New Slip : 0.184\n"
+ ]
+ }
+ ],
+ "prompt_number": 118
+ },
+ {
+ "cell_type": "heading",
+ "level": 2,
+ "metadata": {},
+ "source": [
+ "Example 2.61, Page 202"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "\n",
+ "#Given data :\n",
+ "f=50;#in Hz\n",
+ "P=4;#no. of poles\n",
+ "phase=3;#no. of phase\n",
+ "Pin=60;#in KW\n",
+ "StatorLoss=1.2;#in KW\n",
+ "WindingLoss=1.8;#in KW\n",
+ "S=4;#in %\n",
+ "S=4./100;#in fraction\n",
+ "\n",
+ "#Calculations&Results\n",
+ "Ns=120*f/P;#in rpm\n",
+ "Nr=Ns-Ns*S;#in rpm\n",
+ "print \"Rotor speed(in rpm) :\",Nr;\n",
+ "Pin_rotor=Pin-StatorLoss;#in KW\n",
+ "RotorCuLoss=S*Pin_rotor;#in KW\n",
+ "print \"Rotor Cu Loss(in KW) : \",RotorCuLoss;\n",
+ "Pout_rotor=Pin_rotor-WindingLoss-RotorCuLoss;#in KW\n",
+ "Efficiency=(Pout_rotor/Pin)*100;#in %\n",
+ "print \"Efficiency(in %) :\",round(Efficiency);\n",
+ "HP=Pout_rotor*10**3/735.5;#in H.P.\n",
+ "print \"Horse Power(inH.P.) :\",round(HP,2);"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Rotor speed(in rpm) : 1440.0\n",
+ "Rotor Cu Loss(in KW) : 2.352\n",
+ "Efficiency(in %) : 91.0\n",
+ "Horse Power(inH.P.) : 74.3\n"
+ ]
+ }
+ ],
+ "prompt_number": 195
+ }
+ ],
+ "metadata": {}
+ }
+ ]
+} \ No newline at end of file