Converting 60 Hz Motors to 50 Hz Motors

[ARAMCAWEE]

The power system in the refinery I work in is 50Hz system, while the system in the country is 60Hz. This is due to the fact that we generate our own power without any contribution from the utility company.
My question is that, due to the diffecalities in finding a small 50 Hz motors, a contractor claims taht he can convert the 60Hz (400V) motors to 50Hz (380) to suit our power system by re-winding them in a certain way, so is that really possible? and would't that affected the motors preformance?

 

[hacksaw]

why not, the rpm's will be different(lower) by a factor of 50/60.

before you do it you'll have to have mechanical check the impact on all pumps and other motor driven equipment.

http://www.elec-toolbox.com/Formulas/Motor/mtrform.htm

 

[jbartos]

Suggestion: The 50Hz to to 60Hz converters may also be considered since the two or three motor rewindings may pay for the converter. Also, other 60Hz loads may be connected to a fix frequency 50Hz to 60Hz converter.

 

[jOmega]

Hacksaw ...

What about the "volt-time area" issue of the iron which is designed for 60 Hz frequency... for the same per unit power, you need more iron in a 50 Hz motor.

I remember from a lot of years ago some transformers that smoked on the test floor at Westinghouse when 50 Hz power was applied to them. Seems the Iron was only sufficient for 60 Hz power.... New cores were much bigger for 50 Hz....

 

[Marke]

Hello ARAMCAWEE

You can run a 60Hz 400V motor on 50Hz 380 volts without any problem except that the motor wil run slower, 5/6 speed and the power output of the motor will be lower 5/6 power.
You can not rewind the motor to run at the same speed, or to produce the same power. The 50Hz motor requires more iron/KW and the speed is a unction of the supply frequency.
Best regards,

Mark Empson

http://www.lmphotonics.com

 

[electrical4160kv]

If your motor is 380V, 50 Hz, and the available power system frequency is 60 hz then

V? = 4.44 x Magnetic flux x 60 x 10 raised to -8
380 = 4.44 x Magnetic flux x 50 x 10 raised to -8
Find V?

Cancel Magnetic flux = negligible effect
cancel 10 raised to -8, cancel 4.44
v = 456 volts.

if your motor is 380V, 50 Hz you can connect it directly to available 480v, 60 HZ system. No need to convert the frequency & voltage.

 

[Marke]

OOPs

I missed the vital point on my earlier post.
When you operate a 60Hz motor on 50Hz, you must reduce the applied voltage to 5/6 to retain the correct flux in the iron.
For 400V 60 Hz motors, you need to apply 333 volts at 50 Hz. If the motors are actually wound for 460 volts 60 Hz, then you can apply 380 volts 50 Hz.

Sorry for the omission.
Best regards,

Mark Empson

http://www.lmphotonics.com