690P Drive operating at higher than rated field & torque

Thanks for your reply a lot Daniel.

We tried decreasing the motor RPM to 1336 instead of 1480. Torque became 135% and field 170%.

Even at 45% torque still the field feedback is 130%.

This motor is getting burnt frequently although the voltage and current are less than rated, however the field feedback is very high. What makes the motor field so high?!

The drive is running with parameters V/F shape: LINEAR, Quadratic torque: FALSE. I tried changing them to FAN LAW & TRUE respectively, the result was much higher torque and field feedbacks (although the load is a fan) so i returned to the old values.

The motor is 200kW. The drive is 690PG/1800/460/0011/UK/0/0/0/0/0/115/0. (180 kW @ constant torque / 220 kW @ variable torque)

I hope you can advise me on this issue

It sounds like your motor is being overfluxed.  I would check the data in the Motor Control block to make sure it matches what is actually on the nameplate.  Keep in mind that many nameplates have two rated voltages.  You may need to check the motor's terminal box to know which applies to your case.

Overall, setting the drive to use Fan Law will reduce fluxing and heat.  It is not a bad idea to leave it turned on.  You could also try setting the three boost parameters on the Fluxing block to 0%.

It occurs to me that you were initially running the motor at 1480 RPM, which implies a 50 Hz frequency.  Motors intended to be sold in both the US and Europe (so nearly all of them these days) will usually have a rating for 460 VAC at 60 Hz and one for 400 VAC at 50 Hz.  If the terms got mixed around and you set the drive for 460 VAC at 50 Hz, that would be a problem.

This really sounds like it is related to the configuration.  If you send me your .690 file, I can check it over.  If you don't want to post it on the forum, send me a private message.

The data on the motor nameplate and the Motor control block are matching. The motor (and the original ones) are all rated for 400V @ 50 Hz, same as the parameters. I have sent you all the data in private messages, I hope it will allow you to help me.

What really confuses me is how come the torque is 160% at rated speed although the motor voltage and current are below nameplate rating? Isn't this in contradiction to the Principle of Energy Conservation, as we seem to be getting more power/energy than the drive draws??

It is also strange that the phase current input to the drive is significantly lower than the output current to the motor as measured by the drive, although the in & out voltages aren't that different.

Got your messages -- I responded to them with some answers.  I admit I am very puzzled because I can't find anything wrong in your data.  All of the information you sent makes it look like this motor is operating just fine.

The advice I sent via private message boils down to this:

• See if you can check the motor speed with a hand tachometer.  Perhaps the speed is lower than we think.
• If possible, subject the motor to a megohmeter test to check its insulation.
• Find out if this motor has ever been rewound.  If so, it may not match its nameplate specifications anymore.

One last thing I thought of: check the product code on your drive.  To do this, tap PROG on the keypad and then tap E until you see the drive's power rating.  Make sure the rating shown by the keypad matches what is on the label.  Every now and then, I have a customer with a drive that has undergone maintenance and someone has accidentally overwritten the product code with one that is wrong.  If the product code is wrong, the drive's diagnostics could be wrong as well.