380 volt 60 HZ to 460 volt 60 HZ

[rockfordpi]

Just found out that we got stuck with four 100 HP 380 Volt 60 HZ motors (originally made for job in Brazil, but they were physically too big for the customer’s app).

I know if these would have been 50 HZ, we could reconnect them for 460 volt, 60 HZ. The motor manufacturer even sent us the instructions to do that, but they did not realize that they were 380 60 HZ.

The question is, can these be reconnected to run at 460v 60hz or am I going to have to either sell them with a variable frequency drive or chop out the winding and rewind these brand new motors? I have asked the manufacturer and I am still awaiting an answer from them.

There is a LOT of info online about going from 380 volt 50hz to 460 volt 60hz, but nothing on going from 60hz.

 

[davidbeach]

I'd just throw in a 480V-380Y/220V transformer and call it a day.

 

[DickDV]

While haven't personnally done this, I believe that the addition of a 90VAC bucking autotransformer in the 480VAC supply lines would do the same thing = 380-400VAC at the motor.

 

[waross]

The motors are probably star connected. If so you may reconnect them as 220 Volt delta windings.
In support of DickDV, a pair of 480:240 Volt auto transformers should do the trick.
If you can get a pair of 480:120 Volt boost rated transformers with 5% taps you can get almost 380 Volts. Close enough.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[petronila]

Hello Rockfordpi

Ususally the motors can run with 10 % voltage variation, if the motor is 380 V-60 Hz could work proper at 418 Volts-60 Hz, if the motor is feeded with 460 V this will be experiment an over voltage condition, so you most check the load if the motor is not loaded 100 % I think you can do it in 80% load condition. Other consideration is to take account the motor process important so I suggest to use in not important motors, once the motor fail then you can redesign it to new voltage.

Regards

Carlos

 

[MiketheEngineer]

Call the mfg???

 

[rockfordpi]

Thanks for all the responses. I am Still waiting to hear back from the manufacturer, but I think you guys have already given me what I need.

The answer I am getting from some local guys is that they think it will saturate the iron if we go 480v 60 hz.

Transformer is a possibility as is adding a drive. Unfortunately, the transformer is an extra cost and extra layer of complexity with which most customers will not want to bother.

Ideally someone will come along who needs a motor and a drive or already has a drive and needs a new motor.

 

[Motorwinder]

You'll probably have to rewind them. If it's more than one circuit windings, and it's a delta, you might get by with a reconnect.

The motor shop should be able to do the calculations.

 

[electricpete]

Some NEMA motors have 12 leads, with the possibility to connect series/parallel for high/low voltage (factor of 2 difference) and wye/delta for start/run (factor of sqrt3 difference). An example connection drawing is shown in attachment to the post dated 22 May 11 20:14 in thread: thread237-299276

I doubt that configuration applies to this motor, but if it does (look for 12 leads or check nameplate), then ...assuming the 380vac rating corresponds to the HV (series) run (delta) connection, you could reconfigure the motor for LV (parallel) and start (wye) connection, and the new nominal volts/turn condition would occur with applied voltage of 380 * 2 / sqrt3 = 438vac. 460vac would be only a 5% overvoltage above 438vac, which is tolerable (up to 10% for NEMA motors). No derating would be required.


In the more likely event that you don't have 12-lead motor, I would send one of the motors to a local motor shop to have them take a look at it and tell you your options. There may be some internal reconnection possible at much lower expense than new motor or rewind,


=====================================
(2B)+(2B)' ?

 

[electricpete]

I doubt that configuration applies to this motor, but if it does (look for 12 leads or check nameplate), then ...assuming the 380vac rating corresponds to the HV (series) run (delta) connection, you could reconfigure the motor for LV (parallel) and start (wye) connection, and the new nominal volts/turn condition would occur with applied voltage of 380 * 2 / sqrt3 = 438vac. 460vac would be only a 5% overvoltage above 438vac, which is tolerable (up to 10% for NEMA motors). No derating would be required.

whoops. I got that backwards.... should probably be 380/2*sqrt(3) <380 to obtain nominal volts/turn of reconnected motor... changed in the wrong direction.


=====================================
(2B)+(2B)' ?

 

[rockfordpi]

They are 12 lead motors.

 

[waross]

If you give us the the nameplate information for the wire connections we can probably figure out your allowable voltages. You may even find a usable voltage listed on the nameplate.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[macmckim]

Rockfordpi

Possible the motor supplier derated a 460V motor down to 380V and
reason why the motor is physically too large versus a fatory built motor. What is the frame size of the motor you have?

Mac

 

[rockfordpi]

They are 405TC frames (C-face), but can be changed to 405T by switching the end frame.

 

[macmckim]

Rockfordpi

Frame 405 is standard frame size for a 4P-100HP motor.
Its possible that the motor supplier just derated a standard 460V
to 380V by reducing the SF from 1.15 to 1.0.

You will have to ask you supplier if units were derated from 460 to 380 - then there is no issue about using them in US, or if
supplier built them specially for 380/50.