Rockwell Automation SA3100 AC Power Modules - Manual (Page 116)

F-6 SA3100 Power Modules
F.2 Internal DC Bus Protection
The PMI processor will modify the regeneration or motoring torque limit set by the
programmer during parameter entry (calculated from the maximum current and
overload ratio parameters) to prevent bus voltage from rising (in the case of
regeneration) or falling (in the case of motoring).
During regeneration, if bus voltage reaches the overvoltage threshold, the
regeneration torque limit will be reduced, and will be set to zero if the overvoltage
maximum is reached. During motoring, if bus voltage reaches the undervoltage
threshold, the motoring torque limit will reduced, and will be set to zero if the
undervoltage minimum is reached. The PMI processor will set register 203/1203, bit 4
(WRN_RIL@), to indicate that torque is being limited in either direction.
Note that the PMI processor does not modify the reference provided by the UDC task
to the PMI processor via register 102/1202, TRQ_REF%. If required, the UDC task
can include logic to begin regenerating when DC bus voltage is low.