New 460-V Motor Tripping Breaker Fed By 575-V Source

[Ravenvalor]

Hello,

My textile mill customer called me this morning complaining that their new sprinkler system jockey pump and motor is tripping the breaker. They just sent me some pictures of the new and old motors and everything looks similar with the exception of the fact that the old motor was 575-volts and the new motor is 460-volts. I know that they have 575-volts in the building so I am not surprised by that. I was just wondering whether or not a 460-volt, 3-phase, 3-HP motor would run properly if being fed with 575-volts. It's just a little shocking to me that someone would make such a bad error as to get the voltage on the replacement motor incorrect. Plan to go out there later on today and assess the situation. If anyone has any ideas I would greatly appreciate the advice.

Thanks,

 

[ptonsparky]

I have never seen 575.
No, I wouldn't expect it to work.
A VFD of that size would be reasonably priced, if you can find one in that voltage locally.

 

[ptonsparky]

I have never seen 575.
No, I wouldn't expect it to work.
A VFD of that size would be reasonably priced, if you can find one in that voltage locally.

A VFD of that size is $308 on ....

 

[petersonra]

In lieu of a VFD I would get a transformer. You don't want something on your fire water that might fail and cause an unintentional fire alarm.

 

[augie47]

At 25% over voltage I imagine the smoke leaked out.
No real excuse but so few folks are familiar with 575 volt.
I glanced at some jockey pump catalogs and they don't even list 575v as an option.

 

[Ravenvalor]

Thanks for the great help. I will let you know what I find out.

 

[petersonra]

A VFD of that size is $308 on ....

a 600 V vfd?

 

[jim dungar]

I have never seen 575.
No, I wouldn't expect it to work.
A VFD of that size would be reasonably priced, if you can find one in that voltage locally.

The nominal voltage would 600V, just like having 460V motors on nominal 480V.

 

[Ravenvalor]

Yep it is 575-volts feeding the motor so they are going to have the motor replaced. Thanks for the help.

 

[petersonra]

Yep it is 575-volts feeding the motor so they are going to have the motor replaced. Thanks for the help.

that would make sense.

 

[hillbilly1]

I have never seen 575.
No, I wouldn't expect it to work.
A VFD of that size would be reasonably priced, if you can find one in that voltage locally.

I think 575 is common for our friends to the north. I wired a sheet metal fabrication shop in Atlanta, that brought in a bunch of Canadian equipment that was 575 volts. The plant had a 120/240 volt delta service, so I had to backfeed a 480 to 208 y transformer, as Georgia power wanted something like $60,000 to add the service voltage. Voltage hit right on the money.

 

[petersonra]

I think 575 is common for our friends to the north. I wired a sheet metal fabrication shop in Atlanta, that brought in a bunch of Canadian equipment that was 575 volts. The plant had a 120/240 volt delta service, so I had to backfeed a 480 to 208 y transformer, as Georgia power wanted something like $60,000 to add the service voltage. Voltage hit right on the money.

I put some equipment into a plant down south somewhere one time that was 575 V. I think it was a pulp plant of some sort, but it was a long time ago so it might have made baby food.

I would guess the stuff I have been involved with that went to Canada was about half 480 V and the rest 600 V.

 

[ptonsparky]

a 600 V vfd?

Yes, a low end Auto Direct 3HP, search via phone.

 

[ptonsparky]

https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_soft_starters/ac_variable_frequency_drives_(vfd)

575 volt

 

[Jraef]

At 600V source to a 460V motor (130% over voltage), you are over saturating the motor windings. It will run, but will run VERY hot, so they likely fried the motor winding insulation. In addition, the starting torque from that over fed motor would be 170% of normal, so instead of starting torque being 160% of full load torque, it would be closer to 275% of FLT! It may have cause mechanical damage to couplings, mounts etc. I would suggest to them that they replace everything.