5.1.5 DRV-09 Control Mode
5.1.5.1 V/F Control
The speed of an AC motor when powered by an inverter is controlled by a scalar method. The
most common type of inverter control is referred to as V/F (or V/Hz). This ratio can be
calculated by taking the rated output voltage of the inverter and dividing by the maximum
frequency of the motor. EX: 460V/60 Hz. = 7.67 V/Hz. The ratio can be fixed (linear) or
variable (squared) throughout the speed range. Refer to 5.3.3 BAS-07 V/F (Voltage/Frequency)
Control on page 131 V/F Pattern.
5.1.5.2 Slip Compensation Operation
Slip refers to the variation between the set frequency (speed) and actual motor rotation speed.
During operation at a set frequency, the slip will vary as the load changes. As the load increases,
slip will increase. Slip compensation is used for loads that require compensation of these speed
variations.
Slip Compensation Operation Setting Details
Set DRV-09 to 2 (Slip Compen) to operate in slip compensation mode.
Set the capacity of the motor connected to the inverter.
Enter the number of poles from the motor name plate.
Enter the slip RPM’s from the motor name plate. This may be shown in
Hz. If so, convert to RPM’s. Slip frequency may also be calculated.
=Rated slip frequency
=Rated frequency
=Number of the rated motor rotations
=Number of motor poles
Enter the rated current from the motor name plate.
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