motor rated at 400vac 50hz, using 480vac 60hz 2

[Chiefkocak]

What will happen over time to a motor rated at 400 VAC 50hz operating at 480 vac 60 hz?


Thanks
The C/E on the Kocak

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[Marke]

Hello Chiefkocak

As long as you keep the V/Hz ratio constant, and you do not exceed the insulation voltage, and you do not overload the motor, it will be OK.

400/50 = 480/60, so the V/Hz is the same. This means that the flux will be equal and so you will not suffer from excessive iron losses, and you will get full torque from the motor.

The motor will spin at a higher speed due to the increase in frequency. A two pole motor would operate just below 3000 RPM on 50 Hz and just below 3600RPM on 60 Hz.
This speed increase can raise a problem with the driven load. For example if the driven load is a pump, the input power will be too high for the motor at the higher speed unless it is well underloaded at 50Hz.
If you have a driven load that does not increase linearly with speed, you may consider using an inverter or VSD to reduce the supply to 400V 50Hz.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[edison123]

Upward migration from 50 to 60 Hz involves additional rotational stresses to the motor itself. Motor bearings and fans also must be checked to withstand the 20% more speed. Take the OEM advice on this.

Downward migration from 60 to 50 hz is not a problem mechanically.

*Nothing exists except atoms and empty space; everything else is just an opinion*

 

[DickDV]

The motor will run 20% faster on 60hz than on 50Hz and will attempt to produce the same torque at the higher speed. This results in the available motor kw or hp being 20% higher as well.

In many cases, if these motors are actually loaded to full torque at this higher speed, the motor's thermal capacity is exceeded and overheating is the result. In many other cases, there is enough thermal capacity and the motor stays within its design temperatures.

If the motor is belt- or chain-coupled to the machine, the machine overspeed problem and the over-hp problem can be simultaneously solved by changing sheave or sprocket sizes to increase the mechanical reduction ratio by 20%. Of course, if the power train is all gearing, that is not an easy solution.

 

[jraef]

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