Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 190)

190 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 3 Diagnostics and Protection
Acceleration Fault Anomaly
It is possible for the drive to trip during acceleration on a shear pin fault even
when P434 [Shear Pin Cfg] Bits 0 or 1 in are set. This occurs when the accel time
is set to something very small. The firmware looks at the internal “at speed” bit to
indicate when acceleration is complete. This bit could be set internally faster than
what appears the motor is indicating by sight. For example, if the accel time is set
to something like 0.5 seconds and P434 Bit 0 is set. The drive will most likely trip
on shear pin fault.
There are a couple ways to avoid this.
• Set the accel time longer. This reduces the current requirement.
• Enter a shear pin time longer than the acceleration time.
Using Both Shear Pin 1 and 2
If your application requires a notification of an impending Shear Pin fault. You
can set Shear Pin 1 to give an Alarm at a certain current level, then set Shear Pin 2
Shear Pin - Shock Load
P7 [Output Current] P436 [Shear Pin1 Level] P3 [Mtr Vel Fdbk]
Motor Speed
Shear Point 1 Level
Shock Load
Drive Faults
Seconds
Amps
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