KEB cobmivert F5 VSD motor slowing down problem

[ROAMER_AUS]

Hi all!!!
I have a problem that I never came across before.
KEB combivert F5 drive 15kW running a 9.5kW motor for a drum in an industrial washing machine.
Power board of the drive blew up beyond repair, but control card survived and all parameters were copied into another drive, identical to original.
What is happening now is: as the drive ramps from 70 Hz to a target of 150 Hz (950 RPM drum speed), at some stage motor actually starts slowing down slowly. It reaches about 750 RPM drum speed and then starts slowing down. Watching the parameters, I can see that target frequency is 150 Hz, running frequency is 150 Hz, Drive status is normal "Constant forward" as it should be, and no alarms are present. Only thing that I can see that as the moror keeps slowing down, output kW is rising.
When I go to stop the rotation, drum actually slows down even more, then like the drive "cathes up" to it, speeds it up again to it's normal slow down ramp, and finally stops it completely.

Now can anybody tell me , is this excessive slipping? Is the acceleration ramp too steep? So drive sort of "looses" control of the motor and can not regain it? Or what seems to be the case?

Thanks for the ideas all!!!

 

[jraef]

Sounds as though there is a Current Limit set up in the drive, and a mechanical load issue in which the drive is hitting the current limit, so it is overriding the speed command to maintain that.

To be clear, the Current Limit may have always been there in the original drive programming too, and the mechanical issue may have been what contributed to the failure of that drive. but now with a new fresh drive, it is TRYING to stay running as best it can, at least for now.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[ROAMER_AUS]

Thanks for the taught jraef!!

I triple checked all limitation settings and motor data, and they are all OK.
Steam hose bursted in the machine and sprayed steam directly in to the drive. That's how it died.

 

[iop95]

Seems that was an issue in parameters copy process.
KEB has a lot of copy source/destination settings.
Check actual values of motor pole pairs, base speed/frequency, nominal voltage.
It's an encoder installed? Check parameters.