OV means DC Bus OVERVOLTAGE

The DC Bus voltage exceeded the trip point. For a 240VAC drive the trip point is 410VDC, and for a 480VAC drive it is 820VDC

Common Causes include high input voltage levels at R/L1, S/L2, and T/L3
The decel time is set too short. If the decel time is too short, the inverter will slow down too quickly and the CEMF of the motor will cause the DC Bus Voltage to rise.

Corrective action can include
Check the input voltage to make sure it is correct.
Extend the time in C1-02. Before changing the decel time constant in the inverter contact Milnor Customer Support so we can advise the proper value.


Common Causes that are Milnor Machine specific would be if the belts are too loose on the machine. If the belts are too loose, the motor will free spin, and then the belts will grab, abruptly slowing the motor down. The counter electromotive force (CEMF) will be dissapated back from the motor into the inverter and cause the DC Bus Voltage to rise. If it rises to the trip point, you will get the fault.

CSH 01-14-09