I have been working on an older (90's) style 460 volt 3 phase VFD. Upon slowing down, the precharge contactor slams in and out several times and then gives a drive fault light and has to be reset to run. I also receive an overtemp and drive lock LED. All voltages are stable including the 120 volts across the precharge contactor coil. I have swapped the main control board, power interface board, the options board and all six gate boards with no effect. Has anyone out there experienced this, and what was the fix?

 

Most likely your caps are failing. They can't hold a charge and when the voltage dips, the contactor opens to put the resistor back in the circuit, anticioating a re-start. Keep in mind that caps don't last forever,7 - 10 years at best, and the OmegaPack was an '80s design, not '90s. Square-D was bought by Schneider in 1989 and the OmegaPAck was immediately dumped in favor of the Telemecanique drives, so that makes the OmegaPack at least 25 years old!

 

what is a pre-charge contactor? never heard that term before.

have you tried square d tech support? they are pretty good.

 

i didn't get y r u having a precharge contactor with the vfd. the vfd must not be connected with a contactor.