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LM - Motor Data Parameters
# of Motor Poles = Rated Frequency (Hz) x 120 / Rated Speed (rpm)
= 15 Hz x 120 / 95 rpm
= 18.94 Motor Poles
Here, the number of motor poles is approximately 19. The number is not even.
This would indicate either the motor rated speed or frequency listed on the
nameplate was incorrect. Additionally, it cannot be determined whether the
correct number of motor poles should be either 18 or 20. In this case, contact
the motor manufacturer to conrm.
For this example, assume the motor manufacturer conrmed the number of
pole pairs to be 20. With this, we can assume either the rated motor speed of
95 rpm is correct or the rated motor frequency of 15 Hz is correct, then solve
for the other. Here, we will choose the 95 rpm to be correct and solve for the
rated motor frequency, given a 20 pole motor:
Rated Frequency (Hz) = Rated Speed (rpm) x # of Motor Poles / 120
= 95 x 20 / 120
= 15.8 Hz
Or, equivalently if the rated motor frequency is assumed to be 15 Hz.
Rated Speed (rpm) = Rated Frequency (Hz) x 120 / # of Motor Poles
= 15 x 120 / 20
= 90 rpm
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