75HP 380v 60Hz motor

[Kiljoy]

OK, we have an order for two machines going to Brazil. The voltage there is 380V/3PH/60Hz. We use Weg motors that just happen to be built in Brazil. For some strange reason, they are telling us this is a long lead custom item that will take months to get. IT'S BRAZIL'S STANDARD VOLTAGE AND THE MOTORS ARE MADE THERE!!
Anyway, my question: Is it possible to use 460V/3/60Hz motors and re-nameplate them to 380V/3/60Hz? Would you use the high or low voltage taps (208-230v or 460v). There has been a mixup with our purchasing department and we may need to get these motors ASAP.
I'm thinking that the widings should be large enough on the 230V taps because 380V will draw less amps. I'm sure there are V/Hz ratio considerations and such, but the only information I could find was going between 50Hz and 60Hz, not 60Hz to 60Hz.

 

[itsmoked]

Dick; Brazil is 60Hz. Although it is interesting - there are 4 standards in South America including both frequencies.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Kiljoy]

We have done machines for Saudi-Arabia which are also 380/3/60. The strangest was Namibia with 550V 50Hz. We had to get those custom wound.

 

[Kiljoy]

Thanks again for the information! Here is Weg's solution:
As expected, they plan on re-nameplating standard 460V motors and then running them on the wye configuration. So, it sounds to me that they will use the 230V taps in a paralell wye config because 380V / 1.73 = 230V.

 

[Kiljoy]

Sorry, 230V (219.39)

 

[electricpete]

Just thinking this through:

There is a factor increase in voltage per winding going from series to parallel. The 230 must have been series and the 460 must have been parallel per original nameplate.

There is a factor sqrt(3) increase in voltage per winding going from wye to delta.

So for your explanation to work, it must be that the original winding was series wye and you are reconfiguring to series delta. That's a little different than parallel wye. Or maybe I'm confused (has happened before).

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[electricpete]

Left out a few key words. Let me try again

Just thinking this through:

There is a factor of 2 increase in voltage per winding going from series to parallel. The 230 must have been series and the 460 must have been parallel per original nameplate.

There is a factor sqrt(3) increase in voltage per winding going from wye to delta.

So for your explanation to work, it must be that the original 230 volt winding connection was series wye and you are reconfiguring to series delta. That's a little different than parallel wye. Or maybe I'm confused (has happened before).

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[Kiljoy]

The 12 lead motors we use are either wired in series delta or paralell delta. We only use wye connection if reduced voltage wye-delta starting is required.
I believe using the motor on 460V requires the series delta connection and the 230V configuration requires parallel delta.
This site I found somewhat answers my question.

http://www.usmotors.com/products/ProFacts/1-120-7.htm

 

[davidbeach]

230 would have been the parallel connection and 460 the series connection. Each winding would be rated for 230 and two windings in series would give 460.

 

[electricpete]

Yes, you guys are right. Let me try again:

There is a factor of 2 increase in voltage per winding going from series to parallel. The 230 must have been parallel and the 460 must have been series per original nameplate.

There is a factor sqrt(3) increase in voltage per winding going from wye to delta. If the original winding was suited for 230 in parallel/delta, then could be supplied from sqrt(3)*230 in parallel/wye.

Which is what you said. I had things backwards in my last two messages. Sorry.

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[aolalde]

Only when the 60 HZ motors have 12 leads and connected 460 Volts 1 delta / 230V 2 delta, they could be re-connected in wye 2 circuits.
The new operating voltage 230x1.732 = 398.36into 95.4% of the design voltage while operated with 380 Volts, 60 HZ. That is not the best motor but it will work.

If the frequency should be 50 HZ then the connection will be 1 delta good for 5/6x460= 383.3 Volts, 50 HZ into 99.13% of the optimum voltage when powered with 380 Volts, 50 HZ. The motor power will drop to 5/6x75 = 62.5 HP but a pump will drop the power demand with the cubic power of the speeds ratio (5/6)^3x75 = 43.4 HP

If the motors are already wye connected you need a new winding to make them work at 380 V, 60 HZ.

Check carefully the exact voltage and frequency required.