400V Supply on 460 V motor

[symphonyx]

Can we use 400V-60Hz supply(Philippines)to feed 2hp motor (460V, 60Hz)?
Thanks.

 

[waross]

No. Better plan on an auto transformer.

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

 

[symphonyx]

Ok Thanks....

 

[Marke]

You could, provided that the motor load is much less than the motor rating.
Effectively, the rating of the motor reduces with the voltage.
Best regards,
Mark

Mark Empson
L M Photonics Ltd

 

[burnt2x]

symphonyx,
How many leads out does your 460V motor have? If it has double-winding (230-series winding- delta connected), you could re-wire it to 230V- wye (parallel-230V, wye-connected) and supply 3-phase, 400V.
Can't do this with the usual 6-leads out (single winding) motor! Please try looking at the terminal box cover for a connection diagram and share it with us.

 

[waross]

You can't do it with a standard 9 lead motor either. Delta connections are rare in NEMA motors in small sizes. 12 lead motors are almost nonexistent. Other than that, the reconnection scheme will work fine.

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

 

[symphonyx]

I still haven't received the motor yet. But it is a 230/460V 2 HP Motor (3 phase). I will try to get the diagram later.

@ Marke:
So in order to make it work, when I test the motor, the load amps on the meter should be much less than the the one showed on the motor tag. Is this what you mean? if yes, what is the percentage.


Thanks everybody for the input.

 

[waross]

I wish that I had said this:

For example, a 10% voltage decreasewould cause a 10% amperage increase. This would not be damaging if the motor current stays below the nameplate value. However, if a motor is heavily loaded and a voltage reduction occurs, the current would go up from a fairly high value to a new value which might be in excess of the full load rated amps. This could be damaging. It can be safely said that low voltage in itself is not a problem unless the motor amperage is pushed beyond the nameplate rating. Aside from the possibility of over-temperature and shortened life created by low voltage, some other important items need to be understood. The first is that the starting torque, pull-up torque, and pull-out torque of induction motors, all change based on the applied voltage squared. Thus, a 10% reduction from nameplate voltage (100% to 90%, 230 volts to 207 volts) would reduce the starting torque, pull-up torque, and pull-out torque by a factor of .9 x .9. The resulting values would be 81% of the full voltage values. At 80% voltage, the result would be .8 x .8, or a value of 64% of the full voltage value.

From the Cowern papers on the Baldor motor web-site.

http://www.baldor.com/support/literature_load.asp?LitNumber=PR2525

There are some 200/230/460 volt rated motors around, and some 208/230/460 Volt motors available. One of these may be a better choice.

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

 

[LionelHutz]

It should be OK if the connected load is less than 1.7hp.

 

[ASimmons23]

How about starting time? Anyone see an issue with a prolonged start? I'm thinking about protective devices tripping out to do starting current being applied longer than normal. (maybe not applicable on a 400V system...)

 

[waross]

Starting time may be an issue with higher inertia loads. Many loads allow the motor to reach speed quickly enough that they will start successfully on low voltage. Some motors driving higher inertia loads may have tripping issues.
Definitely an issue to consider.
Re Amps;
The amps will increase as the load increases. Generally you can run pretty close to rated amps. With the lower voltage the current will reach full load current with less applied load. The maximum torque will be less, but motors generally do not operate continuously at maximum torque. (With a few interesting exceptions.)

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