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EEL 3211 Fall 2011 Homework #4
1. The stators of two three phase motors are wired as shown below with V
aa’
= V
m
sin(
ω
t), V
bb’
= V
m
sin(
ω
t+120°) and V
cc’
=
V
m
sin(
ω
t120°).
Determine the direction of rotation for the resulting net magnetic flux density for each stator.
Explain your answers.
At what frequency does the magnetic field of each stator rotate at if
ω
=377 radians/sec?
Determine the direction of rotation for the resulting net magnetic flux density if each stator were rewired by swapping
phases a and c.
Explain your answers.
Determine the speed, in Revolutions Per Minute, that would result if these stators were used to make synchronous motors
assuming that
ω
=377 radians/sec.
Repeat if
ω
=314 radians/sec.
Determine
ω
for each motor if the rotational speed is to equal 1000 rpm.
Figure 1
Figure 2
2. Figure 3 depicts a wire loop that is rotating in the clockwise direction about the axis labeled A in the presence of a constant
and uniformly distributed magnetic flux density
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 Fall '08
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 Flux

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