matching new vfd with old motor applications

[wwsparky]

A 20yr 25hp 585rpm 480v delta 3 phase induction motor, rewound 6 yrs ago supposely, new vfd installation. we are having sporadic random vfd failures. I am thinking this motor was not wound to handle inverter rated applications. Can Aged Motors be properly reworked to todays inverter standards????? What type of tests of the motor can I perform, to qualify this???


Whats your thoughts????

 

[Skogsgurra]

What kind of sporadic failures do you get?

If they are DC link overvoltage, overload, mains failure, stalled motor and such things then you do not have to blame the motor first.

If you think that the motor isn't "VFD hardened" - chances are that it isn't - then a du/dt filter between VFD and motor usually takes care of that.

Gunnar Englund

http://www.gke.org

 

[DickDV]

Generally, when a motor shop rewinds a three phase motor, Class F or better materials will be used even if the original motor was rated to a lesser spec. That would provide a "starter" level vfd motor.

If there are long leads between the motor and the drive, you may still need to take additional steps to protect the motor.

In your case, however, the failures are with the inverter rather than the motor. It is very unlikely that the motor is contributing to the drive failures.

In order to determine cause of drive failure, more information is needed, particularly how it failed or, as mentioned above, if the keypad still functions, what faults are recorded in the drive fault log.

Lacking any of that data, we would be simply speculating and I, for one, have a especially poor record doing that.

More data please.

 

[bigbillnky]

wwsparky,

Do you mean you are having drive faults?(instead of failures, which I interpret to require replacement/ repair)

If you are having faults, please list the fault type/types and any other info you may have and maybe we can help pinpoint possible problems.

Bigbillnky,C.E.F.....(Chief Electrical Flunky)