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LM - Motor Data Parameters
For a given number of motor poles, the rated motor speed or frequency should
be veried against the nameplate values and changed accordingly in the drive,
as rounding may occur on the nameplate. The number of motor poles will
always be an even, whole number. If it is not known, then it may be obtained
from the motor manufacturer based on frame model of the motor.
Motor Calculated Poles on Diagnostic Screen #12 automatically calculates
the number of estimated motor poles, based on LM04 Motor Frequency
and LM02 Motor Speed.
The following equation is used to estimate the number of motor poles. If Motor
Calculated Poles on Diagnostic Screen #12 or the following equation yields a
result near an odd number, contact the motor manufacturer to determine the
correct number of motor poles.
Motor Speed (RPM) =
Rated Motor Frequency (Hz) * 120
# of Motor Poles
LM02 =
LM04 * 120
# of Motor Poles
LM04 =
120
LM02 * # of Motor Poles
# of Motor Poles =
Rated Motor Frequency (Hz) * 120
Motor Speed (RPM)
Once the correct number of motor poles has been determined as a whole,
even number, then the equation can be rearranged to solve for either the rated
motor speed or rated motor frequency, according to the equations above.
It is not important whether the rated motor speed or rated motor frequency
is changed to accurately reect the number of motor poles as long as the
equation holds true, although it may be best to keep the rated motor speed
xed to reect the actual motor speed at high speed and solve for frequency. It
is recommended to perform this calculation to verify no rounding has occurred
for these values on the nameplate motor data. If this equation does not hold
true, the result may be higher current draw to produce a given torque.
Example:
The motor nameplate reads 95 rpm, 15 Hz.
Solving for the number of motor poles, we get:
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