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+{
+ "metadata": {
+ "name": ""
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+ {
+ "cells": [
+ {
+ "cell_type": "heading",
+ "level": 1,
+ "metadata": {},
+ "source": [
+ "Chapter 2: Transformers"
+ ]
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.1, Page number: 63"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import math\n",
+ "\n",
+ "#Variable declaration\n",
+ "Pc=16 #Core loss at Bmax=1.5 T\n",
+ "VIrms=20 #Voltamperess for the core\n",
+ "Vrms=194 #Rms induced voltage(V)\n",
+ "\n",
+ "\n",
+ "#Calculation:\n",
+ "pf=Pc/VIrms\n",
+ "a=math.acos(pf)\n",
+ "I=VIrms/Vrms\n",
+ "Ic=I*pf\n",
+ "Im=I*math.fabs(math.sin(a))\n",
+ "\n",
+ "#Results:\n",
+ "print \"Power factor = \", round(pf,1),\"lagging\"\n",
+ "print \"The core-loss current,Ic =\", round(Ic,3), \"A rms\"\n",
+ "print \"The magnetising current,Im =\", round(Im,2),\"A rms\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Power factor = 0.8 lagging\n",
+ "The core-loss current,Ic = 0.082 A rms\n",
+ "The magnetising current,Im = 0.06 A rms\n"
+ ]
+ }
+ ],
+ "prompt_number": 2
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.2, Page number: 67"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "\n",
+ "#Variable declarations:\n",
+ "k=5 #turns ratio,N1/N2\n",
+ "Z2=1+4j #Impedance of secondary side(ohm)\n",
+ "Vp=120 #primary voltage(V)\n",
+ "\n",
+ "#Calculations:\n",
+ "Z2p=k**2*(Z2)\n",
+ "I=Vp/Z2p\n",
+ "Is=k*I\n",
+ "\n",
+ "#Results:\n",
+ "print \"Primary current:\",complex(round(I.real,2),round(I.imag,2)), \"A rms\"\n",
+ "print \"Current in the short:\",round(Is.real,2)+1j*round(Is.imag,2),\"A\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Primary current: (0.28-1.13j) A rms\n",
+ "Current in the short: (1.41-5.65j) A\n"
+ ]
+ }
+ ],
+ "prompt_number": 53
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.4, Page number: 74"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import cmath\n",
+ "\n",
+ "#Variable declaration:\n",
+ "R1=0.72 #Resistance at high voltage side(ohm)\n",
+ "R2=0.70 #Resistance at low voltage side(ohm)\n",
+ "X1=0.92 #Reactance at high voltage side(ohm)\n",
+ "X2=0.90 #Reactance at low voltage side(ohm)\n",
+ "Zq=632+4370j #Impedance of exciting circuit(ohm)\n",
+ "\n",
+ "#Calculations:\n",
+ "Req=R1+R2\n",
+ "Xeq=X1+X2 \n",
+ "Vcd=2400*Zq/(Zq+complex(R1,X1))\n",
+ "V=complex(round(Vcd.real,2),round(Vcd.imag,3))\n",
+ "\n",
+ "#Results:\n",
+ "print \"Req:\",Req,\"ohm\",\" and Xeq:\",Xeq,\"ohm\"\n",
+ "print \"Voltage at low voltage terminal:\",V,\"V\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Req: 1.42 ohm and Xeq: 1.82 ohm\n",
+ "Voltage at low voltage terminal: (2399.45+0.316j) V\n"
+ ]
+ }
+ ],
+ "prompt_number": 3
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.5, Page number: 76"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import math\n",
+ "\n",
+ "#Variable declaration:\n",
+ "Zf=0.30+.160j #Impedance of feeder(ohm)\n",
+ "Zeq=1.42+3.42j #Equiv.impedance of transformer refd. to primary(ohm)\n",
+ "k=2400/240 #turns ratio\n",
+ "P=50000 #power rating of the transformer(VA)\n",
+ "Vs=2400 #sending end vltage of feeder(V)\n",
+ "\n",
+ "\n",
+ "\n",
+ "#Calculations:\n",
+ "I=P/2400 #Rated current(A)\n",
+ "theta=math.acos(0.80)\n",
+ "Zt=Zf+Zeq #combned impedance of feeder & transformer(ohm)\n",
+ "R=Zt.real\n",
+ "X=Zt.imag\n",
+ "bc=I*X*math.cos(theta)-I*R*math.sin(theta)\n",
+ "ab=I*R*math.cos(theta)+I*X*math.sin(theta)\n",
+ "Ob=(Vs**2-bc**2)**0.5\n",
+ "V2=Ob-ab\n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"The voltage at the secondary terminals:\",round(V2/10,0),\"V\\n\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "The voltage at the secondary terminals: 233.0 V\n",
+ "\n"
+ ]
+ }
+ ],
+ "prompt_number": 4
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.6, Page number: 80"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import cmath\n",
+ "import math\n",
+ "\n",
+ "#Variable declaration:\n",
+ "#short ckt test readings:\n",
+ "Vsc=48 #voltage(V)\n",
+ "Isc=20.8 #current(A)\n",
+ "Psc=617 #power(W)\n",
+ " \n",
+ "#Open ckt test readings:\n",
+ "Vs=240 #Voltage(V)\n",
+ "I=5.41 #current(A)\n",
+ "P=186 #power(W)\n",
+ "V2ph=2400 #voltage at full load at high voltage side(V)\n",
+ "pf=0.8 #lagging power factor at full load\n",
+ "\n",
+ "\n",
+ "\n",
+ "#Calculations:\n",
+ "theta=math.acos(pf)\n",
+ "Zeqh=Vsc/Isc #subscript h refers to high voltage side\n",
+ "Reqh=Psc/Isc**2\n",
+ "Xeqh=math.sqrt(Zeqh**2-Reqh**2)\n",
+ "Ih=50000/V2ph\n",
+ "Pout=50000*pf\n",
+ "Pwind=Ih**2*Reqh\n",
+ "Ptloss=P+Pwind\n",
+ "e=(1-Ptloss/(Ptloss+Pout))*100\n",
+ "Iph=(50000/2400)*complex(math.cos(theta),math.sin(-theta))\n",
+ "V1ph=V2ph+Iph*complex(Reqh,Xeqh)\n",
+ "r=(round(abs(V1ph),2)-2400)*100/V2ph\n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"The efficiency of the transformer:\",round(e,0),\"%\"\n",
+ "print \"Volatge Regulation:\",round(r,2),\"%\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "The efficiency of the transformer: 98.0 %\n",
+ "Volatge Regulation: 1.94 %\n"
+ ]
+ }
+ ],
+ "prompt_number": 6
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.7, Page number: 82"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "\n",
+ "#Varaible declaration:\n",
+ "Vx=2400 #Voltage at low voltage side(V)\n",
+ "Vbc=2400 #Voltage across branch bc(V)\n",
+ "Vab=240 #Voltage induced in winding ab(V)\n",
+ "Pl=803 #transformer losses(W)\n",
+ "pf=0.8 #Power factor of the transformer\n",
+ "\n",
+ "#Calculations:\n",
+ "Vh=Vab+Vbc\n",
+ "Ih=50000/Vab\n",
+ "KVA=Vh*Ih/1000 #Kva rating\n",
+ "P=pf*550000\n",
+ "e=(1-Pl/(P+Pl))*100\n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"Voltage ratings, Vh:\",Vh,\"V \", \"& Vx:\",Vx,\"V\"\n",
+ "print \"KVA rating as an autotransformer:\",KVA,\"KVA\"\n",
+ "print \"full-load efficiency:\", round(e,2),\"%\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Voltage ratings, Vh: 2640 V & Vx: 2400 V\n",
+ "KVA rating as an autotransformer: 550.0 KVA\n",
+ "full-load efficiency: 99.82 %\n"
+ ]
+ }
+ ],
+ "prompt_number": 24
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.8, Page number: 87"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import math\n",
+ "\n",
+ "#Variable declaration:\n",
+ "Vl1=4160 #line-to-line voltage at feeder's sending end(V)\n",
+ "Zf=0.30+.160j #Impedance of feeder(ohm)\n",
+ "Zeq=1.42+3.42j #Equiv.impedance of transformer refd. to primary(ohm)\n",
+ "k=2400/240 #turns ratio\n",
+ "P=50000 #power rating of the transformer(VA)\n",
+ "Vs=2400 #sending end vltage of feeder(V)\n",
+ "\n",
+ "\n",
+ "\n",
+ "#Calculation:\n",
+ "#this problem can be treated on a single phase basis,\n",
+ "#and whole problem is similar to Ex 2.5.\n",
+ "\n",
+ "I=P/2400 #Rated current(A)\n",
+ "theta=math.acos(0.80)\n",
+ "Zt=Zf+Zeq #combned impedance of feeder & transformer(ohm)\n",
+ "R=Zt.real\n",
+ "X=Zt.imag\n",
+ "bc=I*X*math.cos(theta)-I*R*math.sin(theta)\n",
+ "ab=I*R*math.cos(theta)+I*X*math.sin(theta)\n",
+ "Ob=(Vs**2-bc**2)**0.5\n",
+ "V2=Ob-ab\n",
+ "Vload=V2/k\n",
+ "\n",
+ "#Results:\n",
+ "print \"The line to line voltage:\",round(Vload,0),\"V line-to-line\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "The line to line voltage: 233.0 V line-to-line\n"
+ ]
+ }
+ ],
+ "prompt_number": 25
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.9, Page number: 89"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import math\n",
+ "import cmath\n",
+ "\n",
+ "#Variable decclaration:\n",
+ "#All resistances, reactances, & impedances are on per phase basis\n",
+ "Req=1.42 #Series resist. of del-del transformer referred to 2400v side(ohm)\n",
+ "Xeq=1.82 #Series react. of del-del transformer referred to 2400v side(ohm)\n",
+ "Zs=0.17+0.92j #Equiv impedance of sending end transformer(ohm)\n",
+ "Xf=0.8j #Reactance of the feeder(ohm)\n",
+ "Vf=2400 #Voltage of the feeder(V)\n",
+ "k=10 #turns ratio(Vp/Vs)\n",
+ "\n",
+ "\n",
+ "#Calculations:\n",
+ "Zt=(complex(Req,Xeq)/3)+Zs+Xf\n",
+ "Ztot=complex(round(Zt.real,2),round(Zt.imag,2))\n",
+ "If=math.floor(Vf/(math.sqrt(3))/round(abs(Ztot),2))\n",
+ "I1=If/math.sqrt(3)\n",
+ "I2=I1*k\n",
+ "Ic=I2*math.sqrt(3)\n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"Short circuit current in the 2400 feeder, per phase wires:\",round(Ic,1),\"A\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Short circuit current in the 2400 feeder, per phase wires: 5720.0 A\n"
+ ]
+ }
+ ],
+ "prompt_number": 8
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.10, Page number: 92"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import cmath\n",
+ "from math import *\n",
+ "\n",
+ "#Variable declaration:\n",
+ "X1=143 #Reactance of primary(ohm)\n",
+ "X21=164 #Reactance of secondary ref. to primary(ohm)\n",
+ "Xm=163*10**3 #Reactance of magnetising ckt(ohm)\n",
+ "R1=128 #Resistance of primary(ohm)\n",
+ "R21=141 #Resistane of secondary ref. to primary(ohm)\n",
+ "k=20 #turns ratio(2400/120)\n",
+ "V1=2400 #primary voltage(V)\n",
+ "\n",
+ "\n",
+ "\n",
+ "#Calculations:\n",
+ "V2=(V1/k)*complex(0,Xm)/complex(R1,X1+Xm)\n",
+ "mag=abs(V2)\n",
+ "ph=degrees(cmath.phase(V2))\n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"Magnitude of V2:\",round(mag,2),\"V\"\n",
+ "print \"Phase of V2:\",round(ph,3),\"degrees\"\n"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Magnitude of V2: 119.89 V\n",
+ "Phase of V2: 0.045 degrees\n"
+ ]
+ }
+ ],
+ "prompt_number": 10
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.11, Page number: 94"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import cmath\n",
+ "\n",
+ "\n",
+ "#variable declaration:\n",
+ "X1=44.8*10**-6 #Reactance of the primary(ohm)\n",
+ "R1=10.3*10**-6 #Resistance of the primary(ohm)\n",
+ "X21=54.3*10**-6 #Reactance of the secondary refd. to primary(ohm)\n",
+ "R21=9.6*10**-6 #Resistance of secondary ref. to primary(ohm)\n",
+ "Xm=17.7*10**-3 #Reactance of the magnetising ckt(ohm)\n",
+ "k=5/800 #turms ratio(I2/I1)\n",
+ "Zl=2.5+0j #Impedance ofthe load(ohm)\n",
+ "I1=800 #primary current(A)\n",
+ "\n",
+ "#Calculations:\n",
+ "Zp=k**2*Zl\n",
+ "I2=I1*k*Xm*1j/(Zp+R21+(X21+Xm)*1j)\n",
+ "phase=cmath.phase(I2)\n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"Magnitude of current:\",round(abs(I2),2),\"A\"\n",
+ "print \"Phase of the current:\",round(math.degrees(phase),3),\"degrees\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Magnitude of current: 4.98 A\n",
+ "Phase of the current: 0.346 degrees\n"
+ ]
+ }
+ ],
+ "prompt_number": 11
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.12, Page number: 97"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import math\n",
+ "\n",
+ "#Variable declaration:\n",
+ "XL=0.040 #Reactance at l.v side(ohm)\n",
+ "XH=3.75 #Reactance at h.v side(ohm)\n",
+ "Xm=114 #Magnetising reactance(ohm)\n",
+ "RL=0.76*10**-3 #Resistance at l.v.side(ohm)\n",
+ "RH=0.085 #Resistance at l.v.side(ohm)\n",
+ "VA_base=100*10**6 #base VA\n",
+ "V_base=7.97*10**3 #base voltage(V)\n",
+ "\n",
+ "\n",
+ "\n",
+ "#Calculations:\n",
+ "#for l.v side\n",
+ "VA_base=100*10**6 #base VA\n",
+ "V_base=7.97*10**3 #base voltage(V)\n",
+ "Rbase1=Xbase1=V_base**2/VA_base\n",
+ "\n",
+ "#for h.v side:\n",
+ "VA_base=100*10**6 #base VA\n",
+ "V_base=79.7*10**3 #base voltage(V)\n",
+ "Rbase2=Xbase2=V_base**2/VA_base\n",
+ "\n",
+ "XL_pu=XL/Xbase1\n",
+ "XH_pu=XH/Xbase2\n",
+ "Xm_pu=Xm/Xbase1\n",
+ "RL_pu=RL/Rbase1\n",
+ "RH_pu=RH/Rbase2\n",
+ "K_pu=1 #per unit utrns ratio\n",
+ "\n",
+ "#Results:\n",
+ "print \"The per unit parameters are:\"\n",
+ "print \"XL_pu =\",round(XL_pu,3),\"p.u\"\n",
+ "print \"XH_pu =\",round(XH_pu,4),\"p.u\"\n",
+ "print \"Xm_pu =\",math.ceil(Xm_pu),\"p.u\"\n",
+ "print \"RL_pu =\",round(RL_pu,4),\"p.u\"\n",
+ "print \"XL_pu =\",round(RH_pu,4),\"p.u\"\n",
+ "print \"Turns ratio =\",K_pu,\"p.u\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "The per unit parameters are:\n",
+ "XL_pu = 0.063 p.u\n",
+ "XH_pu = 0.059 p.u\n",
+ "Xm_pu = 180.0 p.u\n",
+ "RL_pu = 0.0012 p.u\n",
+ "XL_pu = 0.0013 p.u\n",
+ "Turns ratio = 1 p.u\n"
+ ]
+ }
+ ],
+ "prompt_number": 59
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.13, Page number: 98"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "import cmath\n",
+ "\n",
+ "\n",
+ "#Variable declaration:\n",
+ "Ic=5.41 #Exciting current ref. to low volt. side(A)\n",
+ "k=10 #turns ratio(N1/N2=2400/240)\n",
+ "Vbh=2400 #base voltage at primary side(V)\n",
+ "Vbl=240 #base voltage at secondary side(V)\n",
+ "Ibh=20.8 #base current at primary side(A)\n",
+ "Ibl=208 #base current at secondary side(A)\n",
+ "Z=1.42+1.82j #Equiv.impedance ref.to high voltage side(ohm)\n",
+ "\n",
+ "\n",
+ "\n",
+ "#Calculations:\n",
+ "Zbh=Vbh/Ibh\n",
+ "Zbl=Vbl/Ibl\n",
+ "Icl=Ic/Ibl\n",
+ "Ich=Ic/(Ibh*k)\n",
+ "Zl=Z/(k**2*Zbl)\n",
+ "Zh=Z/Zbh\n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"Per unit exciting current on low volt. sides:\",round(Icl,3,),\"A\" \n",
+ "print \"Per unit exciting current on high volt. sides:\",round(Ich,3),\"A\"\n",
+ "print \"per unit equiv.impedance at low volt. sides:\",round(Zl.real,4)+round(Zl.imag,4)*1j,\"ohm\"\n",
+ "print \"per unit equiv.impedance at high voltage sides:\",round(Zh.real,4)+round(Zh.imag,4)*1j,\"ohm\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Per unit exciting current on low volt. sides: 0.026 A\n",
+ "Per unit exciting current on high volt. sides: 0.026 A\n",
+ "per unit equiv.impedance at low volt. sides: (0.0123+0.0158j) ohm\n",
+ "per unit equiv.impedance at high voltage sides: (0.0123+0.0158j) ohm\n"
+ ]
+ }
+ ],
+ "prompt_number": 12
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.14, Page number: 100"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "from math import *\n",
+ "\n",
+ "\n",
+ "#Variable declaration:\n",
+ "Vb=24000 #Base voltage of secondary of sending end transformer(V) \n",
+ "Z=0.17+0.92j #Impedance of sending end transformer ref. to 2400V side(ohm)\n",
+ "P=150 #Power rating of the transformer(KVA)\n",
+ "V=2400 #Primary voltage of sending end transformer(v)\n",
+ "Ztot=0.64+2.33j #Total series impedance(ohm)\n",
+ "\n",
+ "#Calculations:\n",
+ "Zb=V**2/(P*10**3)\n",
+ "Ztotb=Ztot/Zb\n",
+ "Vsb=1 #Vs in terms of per unit values\n",
+ "Isc=Vsb/abs(Ztotb) #Short current in per unit values(A)\n",
+ "Ib1=P*10**3/(sqrt(3)*2400) #base current of the feeder at 2400V side(A)\n",
+ "If=Ib1*Isc\n",
+ "Ib2=P*10**3/(sqrt(3)*240)\n",
+ "Iscs=Isc*Ib2 #short ckt current at 2400V afeeder side (A)\n",
+ "\n",
+ "#Results:\n",
+ "print \"Short circuit current in 2400 feeder:\",round(Iscs/10**3,2),\"KA\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Short circuit current in 2400 feeder: 5.73 KA\n"
+ ]
+ }
+ ],
+ "prompt_number": 13
+ },
+ {
+ "cell_type": "heading",
+ "level": 3,
+ "metadata": {},
+ "source": [
+ "Example 2.15, Page number: 102"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "from __future__ import division\n",
+ "\n",
+ "#Variable declaration:\n",
+ "P=250*10**3 #power rating of transformer(KVA)\n",
+ "Vp=2400 #primary volatge(V)\n",
+ "Vs=460 #secondary voltage(V)\n",
+ "Pb=100*10**3 #new base power of transformer(KVA)\n",
+ "Vb=460 #new base voltage(V)\n",
+ "Z=0.026+0.12j #series impedance on its own base(ohm)\n",
+ "Vl=438 #load voltage(V)\n",
+ "Pl=95*10**3 #power drawn by the load(kW)\n",
+ "\n",
+ "#Calculations:\n",
+ "Zbo=Vs**2/P #base impedance for the transformer(ohm)\n",
+ "Zbn=Vb**2/Pb #base impedance for the transformer at 100KVA base(ohm)\n",
+ "Zpn=Z*Zbo/Zbn #base impedance at 100KVA base(ohm)\n",
+ "Vpl=Vl/Vb #per unit load voltage(V)\n",
+ "Ppl=Pl/Pb #per unit load power\n",
+ "Ipl=Ppl/Vpl #per unit load current(A)\n",
+ "Vpp=Vpl+Ipl*Zpn #high side voltage of the transformer(V) \n",
+ "\n",
+ "\n",
+ "#Results:\n",
+ "print \"The high side voltage:\",round(abs(Vpp*Vp),0),\"V\""
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "The high side voltage: 2313.0 V\n"
+ ]
+ }
+ ],
+ "prompt_number": 14
+ }
+ ],
+ "metadata": {}
+ }
+ ]
+} \ No newline at end of file