# replacing motors :HELP:



## jklennon (Oct 23, 2009)

The building has boxes all over the place with 277 480 labels but all is dead and I cant find a panel or transformer that makes that voltage.
That was my original plan anyway.

I am pushing toward the Idea of using the 208 but I am not just not sure.

I haven,t worked with over 480 much so just need some advice. Thanks in advance.

Jesse


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## oldtimer (Jun 10, 2010)

jklennon said:


> I am working with a customer that has some mill equipment that was purchased in Austria.
> 
> All motors are 400v 50hz.
> 
> ...


 Please Explain: What do mean, when you ask what voltage should you use to SIZE the motors. The motors have to be sized to comply with the equipment they have to run. The voltage can then be determined to have the best efficiency, with the power available. You may have to consult an electrical engineer.


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## jklennon (Oct 23, 2009)

oldtimer said:


> Please Explain: What do mean, when you ask what voltage should you use to SIZE the motors. The motors have to be sized to comply with the equipment they have to run. The voltage can then be determined to have the best efficiency, with the power available. You may have to consult an electrical engineer.


I really just need help deciding on what voltage to use. i already know what size the motors will be based on the kw rating. What are the pros and cons of each different voltage? How would you guys handle the situation.


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## oldtimer (Jun 10, 2010)

jklennon said:


> I really just need help deciding on what voltage to use. i already know what size the motors will be based on the kw rating. What are the pros and cons of each different voltage? How would you guys handle the situation.


 Go with the higher voltage, I M O.


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## John Valdes (May 17, 2007)

Use the 575 for the motors (bus duct) and the 208 for the single phase panels. That's how the plant is set up. Is this a textile facility?


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## micromind (Aug 11, 2007)

The 400V 50HZ motors won't work on a 600V system. Well, not for very long anyway!

Since you're replacing them, I'd use the 600V system. The motors will be 575V, and are designed to be used on the system you have. 

If you get 208V motors, the wire to them will be larger, and the 11KW (15HP) one will very likely cause a voltage drop on the 208 system during starting. Its starting current will be around 240 amps. 

A 11KW motor on 575V will draw about 90 amps when it starts.

The 600V system will be much more able to handle the starting current.

Rob


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## MDShunk (Jan 7, 2007)

There are a few VFD manufacturers that make drives that will drive those motors on whatever you have available. Telemechanique, for one. Might investigate the cost of drives vs new motors for a minute or two.


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## John Valdes (May 17, 2007)

MDShunk said:


> There are a few VFD manufacturers that make drives that will drive those motors on whatever you have available. Telemechanique, for one. Might investigate the cost of drives vs new motors for a minute or two.


It would most likely not be monetarily efficient to add drives to the mix as you then have the wrong voltage motors with drives.
But you would have an advantage that 480 volt motors could be used in lieu of 575 volt motors.


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## mattsilkwood (Sep 21, 2008)

What I would think about is, is there more than just replacing the motors to this project. 

Are there drives, controls transformers, ect, ect that will have to be replaced as well?

Would it be more simple to just get a transformer for the correct voltage?


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## nitro71 (Sep 17, 2009)

The hertz is off.. Transformer won't fix that. Call the manufactures. Maybe it's the same motor with a different label. Good luck on this. Outa my realm of expertise.


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## miller_elex (Jan 25, 2008)

what about your 120f/#poles synchronous speed?

whats the phase relationship on the windings?


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## mattsilkwood (Sep 21, 2008)

nitro71 said:


> The hertz is off.. Transformer won't fix that. Call the manufactures. Maybe it's the same motor with a different label. Good luck on this. Outa my realm of expertise.


 Good point.


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## John Valdes (May 17, 2007)

mattsilkwood said:


> Would it be more simple to just get a transformer for the correct voltage?


Why is 575 not a correct voltage? It's widely used all over the world and is very common in the southeastern US.
Motors come rated at 575, so do drives. Since 120/208 is available on this system why not use it.



nitro71 said:


> The hertz is off.. Transformer won't fix that. Call the manufactures. Maybe it's the same motor with a different label. Good luck on this. Outa my realm of expertise.


The OP has already stated he was replacing the motors. So he will have the correct hertz and voltage. Like I said above, there is nothing wrong with a 575 volt system and that is what he should be using. It's there and ready to be utilized. 
Why would you install a transformer? That would be silly.


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## MaintenanceGeek (May 18, 2010)

I worked in a facility that was 600vac. We installed a 600vac to 400vac transformer. Next we added a vfd and set it to run @ 50hz. The motors that were used were 400vac.

However I would run the new motors on 600vac. On quick way to start to size 600 volt motors is to find the horse power. This will get you real close to finding the motor amperage draw.


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## frenchelectrican (Mar 15, 2007)

A bit of European motorus will work on 60 HZ supply like the 400 V 50 HZ will work just fine on 480 volts 60 HZ due the V/ HZ ratio is the same but you will may have derate the motor a little due the RPM will be higher and may have to use the VSD to tone it down a little.

Merci.
Marc


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## JohnR (Apr 12, 2010)

mattsilkwood said:


> What I would think about is, is there more than just replacing the motors to this project.
> 
> Are there drives, controls transformers, ect, ect that will have to be replaced as well?
> 
> Would it be more simple to just get a transformer for the correct voltage?


I agree, your control transformers will need to be looked at as well. 
It might be worth while ($) to look up a rotary 3 ph converter for the control circuits. And run the motors at the 600v for larger and 208v for the smaller ones <10Hp
It would be worth it to contact the OEM to get specs on changing the voltage.
I hope you got this equipment at a good price to make it worth the extra effort.


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