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diff --git a/Electric_Machines_by_C._I._Hubert/CHAPTER11.ipynb b/Electric_Machines_by_C._I._Hubert/CHAPTER11.ipynb new file mode 100644 index 00000000..4811ead2 --- /dev/null +++ b/Electric_Machines_by_C._I._Hubert/CHAPTER11.ipynb @@ -0,0 +1,473 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "# CHAPTER11 : DIRECT CURRENT MOTOR CHARACTERISTICS AND APPLICATIONS " + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Example E01 : Pg 448" + ] + }, + { + "cell_type": "code", + "execution_count": 1, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "The armature current = 135.429772662 A\n", + "The resistance rating = 28.952173913 Ohm\n", + "The power rating = 101.069646111 W\n" + ] + } + ], + "source": [ + "# Example 11.1\n", + "# Computation of (a) The armature current when operating at rated conditions \n", + "# (b) The resistance and power rating of an external resistance required in \n", + "# series with the shunt field circuit to operate at 125 percent rated speed\n", + "# Page No. 448\n", + "# Given data\n", + "HP=40.; # hp rating of the device\n", + "Perratedload=0.902; # Percentage rated load\n", + "VT=240.; # Voltage value of motor\n", + "RF=99.5; # Resistance of shunt motor\n", + "Nf=1231.; # Turns per pole of the shunt motor\n", + "Ra=0.0680; # Armature resistance\n", + "RIP=0.0198; # Interpole winding resistance\n", + "Rs=0.00911; # Resistance of series field winding\n", + "Bp1=0.70; # Flux density for a net mmf\n", + "n1=1150.; # Speed of shunt motor\n", + "\n", + "# (a) The armature current when operating at rated conditions\n", + "P=HP*746./Perratedload;\n", + "IT=P/VT; # Total current\n", + "IF=VT/RF; # Field current\n", + "Ia=IT-IF;\n", + "\n", + "# (b) The resistance and power rating of an external resistance required in \n", + "# series with the shunt field circuit to operate at 125 percent rated speed\n", + "\n", + "Fnet=Nf*IF; # Corresponding mmf from magnetization curve\n", + "Racir=Ra+RIP+Rs;\n", + "n2=n1*1.25; # 125 percent rated speed\n", + "# Shaft load is adjusted to value that limits the armature current to 115% \n", + "# of rated current\n", + "Bp2=Bp1*(n1/n2)*((VT-Ia*Racir*1.15)/(VT-Ia*Racir))\n", + "FF=2.3*1000.;\n", + "IF1=FF/Nf;\n", + "Rx=(VT/IF1)-RF;\n", + "PRx=(IF1**2.)*Rx;\n", + "\n", + "# Display result on command window\n", + "print\"The armature current =\",Ia,\"A\"\n", + "print\"The resistance rating =\",Rx,\"Ohm\"\n", + "print\"The power rating =\",PRx,\"W\"\n", + "\n", + "# Note: Answer varies due to round-off errors" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Example E02 : Pg 450" + ] + }, + { + "cell_type": "code", + "execution_count": 2, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "\n", + " Shunt field current = 4.87804878049 A\n", + "\n", + " Armature current = 450.088774014 A\n", + "\n", + " Developed torque = 853.589546189 lb-ft\n", + "\n", + " Armature current if a resistor inserted in series = 476.56458425 A\n", + "\n", + " External resistance required = 17.7013485007 Ohm\n" + ] + } + ], + "source": [ + "# Example 11.2\n", + "# Computation of (a) Shunt field current (b) Armature current (c) Developed \n", + "# torque (d) Armature current if a resistor inserted in series with the shunt \n", + "# field circuit caused the speed to increase to 900 r/min (e) External \n", + "# resistance required in series with the shunt field circuit to operate \n", + "# at 900 r/min\n", + "# Page No. 450\n", + "# Given data\n", + "HP=125.;\n", + "perratedload=0.854; # Percentage rated load\n", + "VT=240.; # Voltage value of motor\n", + "RF=49.2; # Resistance of shunt motor\n", + "Nf=577.; # Turns per pole of the shunt motor\n", + "Ns=4.5;\n", + "Ra=0.0172; # Armature resistance\n", + "RIP=0.005; # Interpole winding resistance\n", + "Rs=0.0023; # Resistance of series field winding\n", + "n1=850.; # Speed of shunt motor\n", + "n2=900.;\n", + "F2=4000.;\n", + "\n", + "# (a) Shunt field current\n", + "\n", + "IF=VT/RF; # Field current\n", + "\n", + "# (b) Armature current \n", + "Pin=HP*746./perratedload; # Input power \n", + "IT=Pin/VT; # Total current\n", + "Ia1=IT-IF;\n", + "\n", + "# (c) Developed torque \n", + "\n", + "Racir=Ra+RIP+Rs;\n", + "Ea=VT-Ia1*Racir; # Armature emf\n", + "Pmech=Ea*Ia1; # Mechanical power\n", + "TD=Pmech*5252./n1/746.; # Torque developed\n", + "\n", + "# (d) Armature current if a resistor inserted in series with the shunt field \n", + "# circuit caused the speed to increase to 900 r/min\n", + "\n", + "Ia2=Ia1*n2/n1;\n", + "\n", + "# (e) External resistance required in series with the shunt field circuit to \n", + "# operate at 900 r/min\n", + "IF2=(F2-0.90*Ns*Ia2)/Nf;\n", + "Rx=(VT/IF2)-RF;\n", + "\n", + "\n", + "# Display result on command window\n", + "print\"\\n Shunt field current =\",IF,\"A\"\n", + "print\"\\n Armature current =\",Ia1,\"A\"\n", + "print\"\\n Developed torque =\",TD,\"lb-ft\"\n", + "print\"\\n Armature current if a resistor inserted in series =\",Ia2,\"A\"\n", + "print\"\\n External resistance required =\",Rx,\"Ohm\"" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Example E03 : Pg 453" + ] + }, + { + "cell_type": "code", + "execution_count": 3, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Speed of the motor = 1713.81 r/min\n" + ] + } + ], + "source": [ + "# Example 11.3\n", + "# Computation of Speed if the load is reduced to a value that causes the \n", + "# armature current to be 30 percent of the rated current\n", + "# Page No.453\n", + "# Given data\n", + "HP=100.;\n", + "perratedload=0.896; # Percentage rated load\n", + "VT=240.; # Voltage value of motor\n", + "Ns=14.; # Number of turns/pole in series field\n", + "Ra=0.0202; # Armature resistance\n", + "RIP=0.00588; # Interpole winding resistance\n", + "Rs=0.00272; # Resistance of series field winding\n", + "n1=650.; # Speed of shunt motor\n", + "Bp2=0.34; # Air gap flux density from magnetization curve\n", + "Bp1=0.87; # Air gap flux density from magnetization curve\n", + "\n", + "# Computation of Speed if the load is reduced to a value that causes the \n", + "# armature current to be 30 percent of the rated current\n", + "\n", + "Pin=HP*746./perratedload; # Input power\n", + "IT=Pin/VT; # Total current\n", + "Ia=IT; # Armature current\n", + "\n", + "Racir=Ra+RIP+Rs; # Resistance of armature circuit\n", + "Fnet1=Ns*Ia*(1.-0.080); # Net mmf\n", + "Fnet2=0.30*Fnet1; # Net mmf from magnetization curve\n", + "n2=n1/((VT-(Ia*Racir))/Bp1 * Bp2/(VT-(0.30*Ia*Racir)));\n", + "\n", + "# Display result on command window\n", + "print\"Speed of the motor =\",round(n2,2),\"r/min\"" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Example E04 : Pg 456" + ] + }, + { + "cell_type": "code", + "execution_count": 4, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "The resistance rating of an external resistance = 25.9636748422 Ohm\n" + ] + } + ], + "source": [ + "# Example 11.4\n", + "# Computation of resistance using linear approximation and values are \n", + "# compared with results obtained in example 11.1\n", + "# Page No. 456\n", + "# Given data\n", + "HP=40.; # hp rating of the device\n", + "percentratedload=0.902; # Percentage rated load\n", + "VT=240; # Voltage value of motor\n", + "RF=99.5; # Resistance of shunt motor\n", + "Nf=1231.; # Turns per pole of the shunt motor\n", + "Ra=0.0680; # Armature resistance\n", + "RIP=0.0198; # Interpole winding resistance\n", + "Rs=0.00911; # Resistance of series field winding\n", + "Bp1=0.70; # Flux density for a net mmf\n", + "n1=1150.; # Speed of shunt motor\n", + "n2=1.25*n1;\n", + "IT=137.84; \n", + "# Computation of resistance using linear approximation and values are \n", + "# compared with results obtained in example 11.1\n", + "\n", + "IF=VT/RF; # Field current\n", + "Ia1=IT-IF; # Armature current\n", + "Fnet1=Nf*IF; # Net mmf\n", + "Racir=Ra+RIP+Rs; # Armature circuit resistance\n", + "Fnet2=Fnet1*(n1/n2)*((VT-Ia1*Racir*1.15)/(VT-Ia1*Racir));\n", + "IF1=Fnet2/Nf; # Field current\n", + "Rx=(VT/IF1)-RF; # External resistance required\n", + "\n", + "\n", + "# Display result on command window\n", + "print\"The resistance rating of an external resistance =\",Rx,\"Ohm\"" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Example E05 : Pg 456" + ] + }, + { + "cell_type": "code", + "execution_count": 5, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "External resistance required in series = 7.74291596939 Ohm\n", + "Error introduced by linear approximation = 56.5004720821 Percent\n" + ] + } + ], + "source": [ + "# Example 11.5\n", + "# Computation using linear approximation to show the gross error that occurs \n", + "# when a linear assumption is applied to compound motors operating at overload \n", + "# conditions\n", + "# Page No. 456\n", + "# Given data\n", + "Nf=577.; # Turns per pole of the shunt motor\n", + "IF=4.88; # Field current\n", + "Ns=4.5; \n", + "IA=450.09; # Armature current\n", + "F2=4367.8; # mmf\n", + "VT=240.; # Voltage value of motor\n", + "RF=49.2; # Resistance of shunt motor\n", + "HP=125.;\n", + "perratedload=0.854; # Percentage rated load\n", + "Rx1=17.8; # Value of resistance in Example 11.2\n", + "\n", + "\n", + "Fnet1=(Nf*IF)+ (0.90 * Ns*IA); \n", + "Ia2=Fnet1*IA/F2; # Armature current\n", + "\n", + "If2=(F2 - Ns*Ia2*0.90)/Nf;\n", + "Rx=(VT/If2)-RF; # External resistance required\n", + "\n", + "# Error introduced by linear approximation\n", + "PE=(17.8-Rx)/17.8*100;\n", + "\n", + "# Display result on command window\n", + "print\"External resistance required in series =\",Rx,\"Ohm\"\n", + "print\"Error introduced by linear approximation =\",PE,\"Percent\"" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Example E06 : Pg 460" + ] + }, + { + "cell_type": "code", + "execution_count": 6, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Torque developed when operating at rated speed = 9062.45895316 lb-ft\n", + "Developed torque required at half rated speed = 2265.61473829 lb-ft\n", + "Armature voltage required for half rated speed = 370.98 V\n" + ] + } + ], + "source": [ + "# Example 11.6\n", + "# Determine (a) Torque developed when operating at rated speed (b) Developed \n", + "# torque required at half rated speed (c) Armature voltage required for half \n", + "# rated speed \n", + "# Page No. 460\n", + "# Given data\n", + "VT=750.; # Voltage value of motor\n", + "Nf=1231.; # Turns per pole of the shunt motor\n", + "Ra=0.00540; # Armature resistance\n", + "RIPcw=0.00420; # Interpole winding resistance\n", + "N=955.; # Speed of shunt motor\n", + "Ia1=1675.; # Armature current\n", + "\n", + "# (a) Torque developed when operating at rated speed \n", + "\n", + "Racir=Ra+RIPcw;\n", + "Ea=VT-Ia1*Racir;\n", + "Pmech=Ea*Ia1;\n", + "TD=Pmech*5252./N/746.;\n", + "\n", + "# (b) Developed torque required at half rated speed \n", + "\n", + "T2=TD*(0.5*N/N)**2.;\n", + "\n", + "# (c) Armature voltage required for half rated speed \n", + "\n", + "Ia2=T2*Ia1/TD;\n", + "V2=(0.5*N/N)*(VT-Ia1*Racir) + Ia2*Racir ;\n", + "\n", + "# Shaft load is adjusted to value that limits the armature current to 115 % of rated current\n", + "\n", + "# Display result on command window\n", + "print\"Torque developed when operating at rated speed =\",TD,\"lb-ft\"\n", + "print\"Developed torque required at half rated speed =\",T2,\"lb-ft\"\n", + "print\"Armature voltage required for half rated speed =\",V2,\"V\"" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Example E07 : Pg 464" + ] + }, + { + "cell_type": "code", + "execution_count": 7, + "metadata": { + "collapsed": false + }, + "outputs": [ + { + "name": "stdout", + "output_type": "stream", + "text": [ + "Resistance of the dynamic braking resistor = 0.56222252364 Ohm\n" + ] + } + ], + "source": [ + "# Example 11.7\n", + "# Computation of the resistance of a dynamic braking resistor that will be \n", + "# capable of developing 500 lb-ft of braking torque at a speed of 1000 r/min.\n", + "# Page No. 464\n", + "# Given data\n", + "T1=910.; # Torque load\n", + "Pshaft=199.257*746.; # Power of shaft\n", + "eeta=0.940; # Efficiency\n", + "VT=240.; # Rated voltage\n", + "T2=500.; # Braking torque\n", + "n1=1000.; # Windage and friction speed\n", + "n2=1150.; # Speed of motor\n", + "Rf=52.6; # Field resistance\n", + "Racir=0.00707; # Combined armature,compensating winding and # interpolar resistance\n", + "\n", + "# Resistance of a dynamic braking resistor\n", + "Pshaft=T1*n2/5252.; # Shaft power \n", + "Pin=Pshaft*746./eeta; # Input power\n", + "IT=Pin/VT; # Total current \n", + "If=VT/Rf; # Field current\n", + "Ia1=IT-If; # Armature current\n", + "Ea1=VT-Ia1*Racir; # Armature emf\n", + "\n", + "Ia2=Ia1*T2/T1; # Armature current\n", + "Ea2=Ea1*n1/n2;\n", + "RDB=(Ea2-Ia2*Racir)/Ia2; # Resistance\n", + "\n", + "# Display result on command window\n", + "print\"Resistance of the dynamic braking resistor =\",RDB,\"Ohm\"" + ] + } + ], + "metadata": { + "kernelspec": { + "display_name": "Python [Root]", + "language": "python", + "name": "Python [Root]" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 2 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython2", + "version": "2.7.12" + } + }, + "nbformat": 4, + "nbformat_minor": 0 +} |