Rockwell Automation Publication 6000-TD004D-EN-P - November 2017 15
Functional Descriptions Chapter 1
Rated Frequency
This function is used to the set the drive's rated frequency parameters and also
the frequency limit. Frequency dead zone setting is used to limit the low
frequency starting range, and prevent output fluctuations when the drive is in
analog input mode and the frequency is around zero Hz. Frequency amplitude
limit is used to limit the amplitude of set frequency, thus it prevents the set
frequency from exceeding the drive's maximum output frequency.
Parameter Rated Output Frequency (P460) is the drive’s rated output frequency.
The frequency value ranges from 0...75 Hz and should be set equal to the motor’s
rated frequency. If Rated Output Frequency is not set correctly it may cause
damage to the motor.
Parameter Maximum Output Frequency (P466) is the drive’s maximum output
frequency. Rated Output Frequency cannot be set higher than Maximum Output
Frequency. Any attempt to do so will fail.
If the original setting-frequency is lower than parameter Frequency Command
Deadband Upper Limit (P414), frequency dead zone setting can change the
setting- frequency to equal Frequency Command Deadband Upper Limit.
Frequency amplitude limit can limit the setting-frequency between parameters
Frequency Command Lower Limit (P413) and Frequency Command Upper Limit
(P415). Following the rule:
Frequency Command Upper Limit > Frequency Command Lower Limit > 0
This function is used to limit the amplitude for setting-frequency. This prevents
the setting-frequency from becoming bigger than the drive’s maximum output
frequency.
Stop Mode
There are two methods in which a PowerFlex 6000 drive can use to stop – ramp
down and coast stop.
The stop mode can be selected by setting Stop Method (P024) to “1” for coast
stop and “0” for ramp down.
If coast stop was selected, you must wait for a certain time to elapse before
restarting the drive. The time is determined by the formula:
Time = Motor Coast Stop Time (P253) * frequency before stop / max frequency
If ramp down was selected, the motor will ramp down.
Parameters Frequency Command-Low Frequency Region Boundary (P251) and
Delayed Lockout Time of Stop Operation (P270) are also used in this function.
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