Table 2.2 – maximum slip per number of poles -8 – Rockwell Automation SA3100 Distributed Power System Drv Config,Program User Manual
Page 20
2-8
SA3100 Drive Configuration and Programming
If a warning appears, it is likely that the maximum RMS current that can be supplied
to the motor at the torque overload ratio level selected is too high for the Power
Module selected. See Appendix E for more information on determining the
maximum RMS current that will result from the ratio entered.
•
Frequency at Rated Voltage (Hz) (Range: 1 to 600)
This value is used to determine the frequency at which the motor enters the
constant power range. Enter the value in Hz. Resolution is 0.1 Hz. There is no
default value.
•
Rated Full Load Speed (RPM) (Range: 10 to 10,000)
This value is used to determine the rated slip of the motor at the rated motor
frequency. This value is found on the motor’s nameplate. Enter the value in RPM.
The resolution is 1 RPM. There is no default value.
•
Motor Poles (2, 4, 6, 8, 10, 12, 14, or 16)
This value is used to determine the relationship between drive output frequency
and motor shaft speed. Because this number is not readily available, the number of
motor poles will be calculated automatically based on the other parameters you
have entered and will be displayed on the screen. You must then select this
calculated value from a list of the preset values. There is no default value.
The following formula will be used to calculate the number of motor poles:
120
∗
Frequency at Rated Voltage / Rated Full Load Speed
The resulting number will be rounded down to the nearest whole even number.
Note that this formula may not result in the correct number of motor poles if you are
using a high slip motor, such as a NEMA design D motor. See table 2.2 for the
maximum slip per number of motor poles that will result in a correct calculation.
For example, on an 8-pole motor, if slip is greater than 19%, the calculated value
will be incorrect. You must then enter the correct value.
Table 2.2 – Maximum Slip Per Number of Poles
Number of Poles
Maximum Slip
2
49%
4
33%
6
24%
8
19%
10
16%
12
14%