# Chapter 5 - Magnetic Properties of Materials¶

## Exa 5.1 page 237¶

In [1]:
# given data
Area_hysteresis_curve=9.3 #in cm**2
Cordinate1_1cm=1000 #in AT/m
Cordinate2_1cm=0.2 #in T
#Part (i)
hysteresis_loss=Area_hysteresis_curve*Cordinate1_1cm*Cordinate2_1cm #in J/m**3/cycle
print "Hysteresis loss/m**3/cycle = %0.2f J/m**3/cycle "%(hysteresis_loss)
#Part (ii)
f=50 #in Hz
H_LossPerCubicMeter=hysteresis_loss*f #in Watts
print "Hysteresis loss Per Cubic Meter = %0.2f kW"%(H_LossPerCubicMeter*10**-3)

Hysteresis loss/m**3/cycle = 1860.00 J/m**3/cycle
Hysteresis loss Per Cubic Meter = 93.00 kW


## Exa 5.2 page 237¶

In [2]:
# given data
Area_hysteresis_loop=93 #in cm**2
scale1_1cm=0.1 #in Wb/m**2
scale2_1cm=50 #in AT/m

hysteresis_loss=Area_hysteresis_loop*scale1_1cm*scale2_1cm #in J/m**3/cycle
print "Hysteresis loss/m**3/cycle = %0.2f J/m**3/cycle "%(hysteresis_loss)

f=65 #unit less
V=1500*10**-6 # in m**3
P_h=hysteresis_loss*f*V
print "Hysteresis loss is : %0.2f"%(P_h)," W"

Hysteresis loss/m**3/cycle = 465.00 J/m**3/cycle
Hysteresis loss is : 45.34  W


## Exa 5.3 page 237¶

In [3]:
from math import floor
# given data
nita=628 # in J/m**3
B_max=1.3 # in Wb/m**2
f=25 # in Hz
ironMass=50 # in kg
densityOfIron=7.8*10**3 # in kg/m**3
V=ironMass/densityOfIron
x=12.5 # in AT/m
y=0.1 # in T
# formula Hysteresis loss/second = nita*B_max**1.6*f*V
H_Loss_per_second = nita*B_max**1.6*f*V  # in J/s
H_Loss_per_second=floor(H_Loss_per_second)
H_Loss_per_hour= H_Loss_per_second*60*60 # in J
print "Hysteresis Loss per hour is : ",(H_Loss_per_hour)," J"
# Let Hysteresis Loss per m**3 per cycle = H1
H1=nita*B_max**1.6
# formula  hysteresis loss/m**3/cycle = x*y*area of B-H loop
Area_of_B_H_loop=H1/(x*y)
Area_of_B_H_loop=floor(Area_of_B_H_loop)
print "Area of B-H loop is : ",(Area_of_B_H_loop)," cm**2"

Hysteresis Loss per hour is :  550800.0  J
Area of B-H loop is :  764.0  cm**2


## Exa 5.4 page 237¶

In [4]:
from __future__ import division
# given data
H_L_per_M_Cube_per_C=380 # in W-S
f=50 # unit less
density=7800 # in kg/m**3
V=1/density # in m**3
# formula Hysteresis loss = Hysteresis loss/m**3/cycle * f * V
P_h=H_L_per_M_Cube_per_C * f * V
print "Hysteresis loss is : %0.2f"%(P_h), "W"

Hysteresis loss is : 2.44 W


## Exa 5.5 page 239¶

In [5]:
# given data
P_e1=1600 # in watts
B_max1=1.2 # in T
f1=50 # in Hz
B_max2=1.5 # in T
f2=60 # in Hz
# P_e propotional to B_max**2*f**2, so
P_e2=P_e1*(B_max2/B_max1)**2*(f2/f1)**2
print "Eddy current loss is : ",(P_e2)," watts"

Eddy current loss is :  3600.0  watts