Excercises Electric Machinery Fundamentals

Chapter 6 Problem 6-2



In [1]:

    
%pylab inline









    



Populating the interactive namespace from numpy and matplotlib

Answer the questions in Problem 6-1 for a 480-V three-phase two-pole 60-Hz induction motor running at a slip of 0.025.



In [2]:

    
fse = 60.0  # [Hz]
p   =  2.0
s   =  0.025

The speed of the magnetic fields is:

$$n_\text{sync} = \frac{120f_{se}}{p}$$



In [3]:

    
n_sync = 120*fse / p
print('''
n_sync = {:.0f} r/min
==================='''.format(n_sync))









    



n_sync = 3600 r/min
===================

The speed of the rotor is:

$$n_m = (1-s)n_\text{sync}$$



In [4]:

    
n_m = (1 - s) * n_sync
print('''
n_m = {:.0f} r/min
================'''.format(n_m))









    



n_m = 3510 r/min
================

The slip speed of the rotor is:

$$n_\text{slip} = s\cdot n_\text{sync}$$



In [5]:

    
n_slip = s * n_sync
print('''
n_slip = {:.0f} r/min
================='''.format(n_slip))









    



n_slip = 90 r/min
=================

The rotor frequency is:

$$f_{re} = \frac{p\cdot n_\text{slip}}{120}$$



In [6]:

    
fre = p * n_slip / 120
print('''
fre = {:.1f} Hz
============'''.format(fre))









    



fre = 1.5 Hz
============