ECN Forum Forums General Topics of the Trade General Discussion Area 480 or 460 volt secondary ?

NEMA standards ask that motors operate at + or - 10% of the Nameplate voltage.
Transformers have a variety of places where you may connect the wires, to "adjust" the voltage to what you want. It is well within the range of these 'taps' to set them at 460- just ask the guy to do it when he hooks it up.

Is there not a manual or a spec sheet for the machine with a min and max voltage range? Since the machine includes electronic equipment, I would expect such a specification.

A 460V motor is intended to be run on a 480V nominal system. You do not have to worry about +/- operating range, nor do you have to adjust your transformer taps.

There is no major manufacturer of 480V or 600V or 240V three phase motors.

There is no major manufacturer of standard design 60hz power transformers with nominal voltage inputs and utilization voltage outputs (i.e. 600-460).

The "guy" hooking it up is me and whenever I ask him something I get weird looks from other people


No Manual as of yet, just a request fron "the boss" to size a transformer for a 60 amp 460 volt machine.


I do understand this,I was mostly looking for a little reassurance after being questioned by a fellow electrician, always like to make sure I didn't miss something.

It is hard to provide reassurance for something that doesn't exist.

They do not make 480V motors. 460V is not a nominal supply voltage, yet the NEC (US for sure and the CNEC probably) says to make all calculations using nominal voltages.

Don't you have the same problem with 575V motors on a 600V system?

As Long as you do not have more than a 10% voltage variance from nameplate values at the machine you will be fine.
As long as you keep it within that magic number there no noticeable loss in life expectancy or torque reduction.
Also it's better to be a little high rather than low.If you ask me 5% high is perfect since you will be shipping this machine out and you have no control over the customers supply voltage.It's all relative to the machines new home or in this case homes.
cheers

[This message has been edited by frank (edited 02-11-2006).]

Frank,
We are receiving this machine,not shipping it out.

Bigrockk,
What kind of voltage do you normally enjoy at your plant? Is it low or high to begin with?
Or a little from column A, a litle from column B?

I just asked a Leader in machine tool and either a 460v or a 480v xformer will do but if it has a PLC,VFD or Soft Start try to stay at or above 460.What ever you can get cheaper or have in stock would be his main consern.Since you can,check what your 600v supply actualy is and go from there.A Poco owned xformer gives supplies us 640v and they won't repace it because we don't have any problems.
cheers

[This message has been edited by frank (edited 02-11-2006).]

Stay at 480V, that is your nominal supply system voltage, you have no choice.

You will not find a standard 480V motor. You will not find a standard 600->460V transformer nor even a 480->460V one.

460V motors are designed and intended to be used on nominal supply systems of 480V +/- 10% (528 to 432). You do not need to make any accommodations unless you are outside of this range at the motor terminals. All of the motor performance information, including full load current, are based on a nominal supply voltage of 480V.

Look around, I am sure you do not have 600->575V transformers to feed all of the motors in your plant.