Home Forums General Discussion Technical Questions Tac 50-04 644 fault

I've got a tac 50-04 that keeps getting 644 faults (instantaneous Regen over current). The car will be just fine sitting stationary, or after 1-3 runs. Any more than that and it will pop the fault and not be able to clear it until power has been killed and the DC bus bleeds off. Does anyone have any idea what I'm dealing with here?

Drive is a pwm-dc regenerative drive. 460vac 120hp

This car also had 2 of the w- IGBT fail within the last month, but ran well for about a month after I replaced the second one with proper torque and heatsink compound. I didn't know about the torque and compound when I replaced the first one.

Thank you for any responses.

Does it always happen in a regen situation i.e. up empty or down heavy? Or does it happen at other times or even at rest. If you haven’t already you should zero out the bus voltage error on the regen card. Hook your meter from LCOM to VERR test points and adjust R73 pot to as close to zero as possible but stay on the positive side.