Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 258)

258 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 4 Motor Control
Min/Max Fwd/Rev Speed
Maximum and minimum speed limits are applied to the forward and reverse
reference. The minimum speed limits create a band that the drive will not run
continuously within, but ramps through. This is due to the forward or reverse
minimum speeds, P522 [Min Fwd Speed] and P523 [Min Rev Speed]
respectively. If the reference is positive and less than the Min Fwd Speed, it is set
to the Min Fwd Speed minimum. If the reference is negative and greater than
Min Rev Speed minimum, it is set to the Min Rev Speed minimum. If the
minimum is not 0, hysteresis is applied at 0 to prevent bouncing between the Min
Fwd Speed and Min Rev Speed minimums. If the reference is greater than the
forward or reverse maximum speeds, P520 [Max Fwd Speed] and P521 [Max
Rev Speed] respectively, the speed reference is clamped to the their respective
maximum limit.
See example below:
• P520 [Max Fwd Speed] = 60 Hz
• P521 [Max Rev Speed] = -60 Hz
• P522 [Min Fwd Speed] = 20 Hz
• P523 [Min Rev Speed] = -20 Hz
• P545 [Spd Ref A Sel] = P546 [Spd Ref A Stpt]
The picture below depicts how the Min/Max Fwd/Rev Speed bands and its
influence the drive. The BLUE line depicts the desired speed reference (set point)
522
523
520
521
1103 5
Speed Ref Limits
Min Speed Limits Max Speed Limits
Limit Limit
Min Fwd Speed
Min Rev Speed
Max Fwd Speed
Max Fwd Speed
Internal Load Dependent
Max Limit (Lift Application)
Trq Prove Status
(LoadTestActv) PowerFlex 755