# Electric Machinery Fundamentals 5th edition

## Example 1-1:

Import the PyLab namespace (provides set of useful commands and constants like Pi)

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In [1]:

%pylab inline

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Populating the interactive namespace from numpy and matplotlib

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Define all the parameters:

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In [2]:

l1 = 0.45                 # Length of region 1
l2 = 1.3                  # Length of region 2
a1 = 0.01                 # Area of region 1
a2 = 0.015                # Area of region 2
ur = 2500                 # Relative permeability
u0 = 4*pi*1e-7            # Permeability of free space
n = 200                   # Number of turns on core
i = 1                     # Current in amps

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Calculate the first reluctance:

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In [3]:

r1 = l1 / (ur * u0 * a1)

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Calculate the second reluctance:

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In [4]:

r2 = l2 / (ur * u0 * a2)

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Calculate the total reluctance

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In [5]:

rtot = r1 + r2

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Calculate the mmf

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In [6]:

mmf = n * i

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Finally, get the flux in the core:

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In [7]:

flux = mmf / rtot

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#### Display the result:

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In [8]:

print('r1 = {}'.format(r1))
print('r2 = {}'.format(r2))
print('Flux = {}'.format(flux))

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r1 = 14323.944878270579
r2 = 27586.856802595194
Flux = 0.004772039473807281

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(I'm using the new style PyFormat in order to make the output above a bit nicer.)