# Variables
kVA = 250.; #kVA
V1 = 11000.; #V(Primary voltage)
V2 = 400.; #V(secondary voltage)
f = 50.; #Hz
N2 = 80.; #no. of turns in secondary
# Calculations and Results
Ifl1 = kVA*1000/V1; #A(Full load primay current)
Ifl2 = kVA*1000/V2; #A(Full load secondary current)
print ("Part(a)");
print "Full load primary current(A) %.2f"%Ifl1
print "Full load secondary current(A) : %.2f"%Ifl2
print ("Part(b)");
N1 = N2*V1/V2; #no. of turns in secondary
print "No. of turns in primary : %.2f"%N1
print ("Part(c)");
fi_m = V2/(4.44*N2*f); #Wb
print "Maximum value of flux(mWb) : %2.f"%(fi_m*1000)
import math
# Variables
N1 = 480; #no. of turns in primary
N2 = 90; #no. of turns in secondary
lfp = 1.8; #m(length of flux path)
ag = 0.1; #mm(airgap)
Flux = 1.1; #T(flux density)
MF = 400; #A/m(Magnetic flux)
c_loss = 1.7; #W/kg
f = 50; #Hz
d = 7800; #kg/m**3(density of core)
V = 2200; #V(potential difference)
# Calculations and Results
#Part (a)
fi_m = V/(4.44*N1*f); #Wb
A = fi_m/Flux; #m**2(Cross sectional area)
print "(a) Cross sectional area(m**2) : %.2f"%A
#Part (b)
Vnl2 = V*N2/N1; #V(2ndary voltage on no load)
print "(b) 2ndary voltage on no load(V) : %.f"%Vnl2
#Part (c)
Fm1 = MF*lfp; #A(Magnetootive force for the core)
Fm2 = Flux/(4*math.pi*10**-7)*ag*10**-3; #A(Magnetootive force for airgap)
Fm = Fm1+Fm2; #A(Total magnetomotive force)
Imax = Fm/N1; #A(maximum value of magnetizing current)
Iom = Imax/math.sqrt(2); #A(rms current)
v = lfp*A; #m**3(Volume of core)
m = v*d; #kg(Mass of core)
coreLoss = c_loss*m; #W(Core Loss)
Io1 = coreLoss/V; #A(Core loss component of curent)
Io = math.sqrt(Iom**2+Io1**2); #A(no load current)
print "(c) Primary current on no load(A) : %.2f"%Io
pf = Io1/Io; #lagging pf on no load
print "(c) Power factor(lagging) on no load : %.2f"%pf
# Variables
N1 = 1000; #no. of turns in primary
N2 = 200; #no. of turns in secondary
I0 = 3; #A
pf0 = 0.2; #lagging power factor
I2 = 280; #A(2ndary current)
pf2 = 0.8; #lagging power factor
# Calculations and Results
I2dash = I2*N2/N1; #A
cosfi0 = pf0;cosfi2 = pf2;sinfi0 = math.sqrt(1-cosfi0**2);sinfi2 = math.sqrt(1-cosfi2**2);
I1_cosfi1 = I2dash*cosfi2+I0*cosfi0; #A
I1_sinfi1 = I2dash*sinfi2+I0*sinfi0; #A
I1 = math.sqrt(I1_cosfi1**2+I1_sinfi1**2); #A
print "Primary current(A) : %.1f"%I1
fi1 = math.degrees(math.atan(I1_sinfi1/I1_cosfi1)); #degree
pf1 = math.cos(math.radians(fi1)); #lagging
print "Primary power factor(lagging) : %.2f"%pf1