powerflex 755 110kw F13 ground fault

[Nandraj]

Dear All,
please i need urgent help for my powerflex 755 110kw, F13 ground fault . as it occurs in 2-3 times in day and after resetting its OK again
also the F13 fault followed by F12 hw over current faults comes . after resetting its OK runs the drive .
i tried to check all i didn't find any short to ground in either side

 

[gclshortt]

http://www.plctalk.net/qanda/showthread.php?t=87475

http://www.plctalk.net/qanda/showthread.php?t=54045

http://www.plctalk.net/qanda/showthread.php?t=58735

The above threads may help you out.
Regards,

 

[milldrone]

Dear All,
please i need urgent help for my powerflex 755 110kw, F13 ground fault . as it occurs in 2-3 times in day and after resetting its OK again

i tried to check all i didn't find any short to ground in either side

This sounds like the classic intermittent type of fault. Very hard to find because it's not there when you test for it.

Read the threads gclshortt mentioned, if possible try to isolate the problem to either the motor, cable, or drive.

If it only happens 2-3 times a day you may have to "test" this for an extended period of time, 2 days to be sure enough time has passed for the fault to reappear.

Edit: One of my favorite tools for trouble shooting intermittent problems is an ordinary home use security digital video recorder. most of these can record several cameras at the same time and play them back in sync. I just noticed you have a rather large motor, so substituting cables, motors and drives is likely a problem . My suggestion for your situation is to put a analog amp clamp set for 5 or 6 amps around all three power leads. This way any stray current will show up on the meter. then record the meter with the DVR. There will be a time stamp to aid you when the problem occurs.

 

[collinsd70]

Have you tested the motor under stress with a Megger Tester?

 

[Nandraj]

hi ,
i also check running current its around 111.2A, 112.4A,113.7A

 

[milldrone]

. My suggestion for your situation is to put a analog amp clamp set for 5 or 6 amps around all three power leads. This way any stray current will show up on the meter. then record the meter with the DVR. There will be a time stamp to aid you when the problem occurs.

hi ,
i also check running current its around 111.2A, 112.4A,113.7A

I can see now how my suggestion about amp clamping the vfd output leads might have not been perfectly clear.

When you pass all three leads through the single jaw at the same moment, the only current the ammeter will record is the current not on the motor leads (ground fault). So while the motor is running without a ground fault the ammeter will display 0. Only during a ground fault condition will the ammeter display any current. Secondly if this only happens 2-3 times a day someone will have to watch the meter 100% of the time, hence my suggestion of a video recorder. Your original post indicated there was also a hardware over current at the same time. Hopefully this will allow enough current to flow that it can be detected by the amp clamp. Also this is where a analog meter pays off rather than a digital unit with an auto off and display smoothing can affect the reading.

 

[jraef]

So do you know how to use the Rockwell Knowledgebase system for looking at things like this? I suggest starting there.


https://rockwellautomation.custhelp.com/app/answers/detail/a_id/60178 this is a general posting about troubleshooting GF trips on PowerFlex drives.


https://rockwellautomation.custhelp.com/app/answers/detail/a_id/900207
This one is more specific to the PF750 series IF the troubleshooting procedures in the above don't help, addressing a known bug on Frame 7 drives where the manufacturing date is between 01-JUN-2013 and 23-AUG-2016. 110kW at 400VAC Normal Duty would typically be a Frame 6, but you are right on the edge so if it was sized as Heavy Duty is would be a Frame 7.

 

[Nandraj]

Have you tested the motor under stress with a Megger Tester?

yyes i got megger value is around 220Mohm all three winding