Yaskawa, Over current Fault with no motor connected

have a Yaskawa Z1000 125HP drive tripping oC (over current).

I have disconnected the motor and every time I power up the drive I get that fault. I have check the fan and bypass fan circuit and still get that fault .I also performed a static check on diodes and transistors and it passed.

model number of drive is =CIMR-ZU4A0156AAA

Please help

Generally, if output IGBT's are shorted, you will get an Overcurrent Fault but only when you put the drive in Run mode; not when powered up but not running.

How about checking that. Just when does the fault occur?

I agree with DickDV, that's the first thing I would suspect. Generally speaking, current is sensed on either the DC bus just ahead of the transistors or on the output side of the transistors. If it is sensed on the input side, a bad transistor could be leaking to ground but only under voltage stress, but your meter is only putting 9VDC on it for a diode check and the resistance to ground makes it look OK to you. If on the output side, you could have a bad firing circuit that immediately fires at least two transistors as soon as it is energized. In that case, the logic is often looking for even tiny amounts of current flow, because ANY current flow when there is no command to fire the transistors coming from the mP means trouble, so the drive trips off. More sophisticated drives will separate that out as a failed device, but less expensive ones just lump any current related fault as OC.

The people to call who know enough about how that all takes place are.... Yaskawa!

existing or new installation ?

thanks guys I really appreciate.

DickDv : it only happens when I power the drive.

osmanmom : it is existing drive that has been runing for 6 moth only

check the motor condition and megger test the motor.


https://www.yaskawa.com/pycprd/support/support-overview/tab6/link60

Sorry ag343 but you didn't really answer my question. When you say you "power the drive" are you referring to powering up the input but not putting the drive in run mode, or are you referring to powering the motor by changing the drive to run mode.

There must be a motor on the output, as the voltage will rocket when open outputs.
the fault should say over voltage

Hello dickdv,

Yes ur right every time i put the drive to run it go up to 3hz then fault over current how can I check IGBT?

I have had Sensor failure in a Yaskawa Drive. In my case it was a Ground Fault. I ended up replacing the VFD, and sending it in for repair.

Stu....

I'd call Yaskawa tech support and see what your options are. I've always ended up just replacing the drive when it throws codes without a motor connected.

I agree IGBT's are gone if faulting with no motor connected