HomeFrequency Converter50Hz motor running on 60Hz power supply

50Hz motor running on 60Hz power supply

On the 3 phase motor, you will have the following:
1. Hz on a 50 Hz - will turn slower ~20%. Since it's slower, cooling on the motor required less. It will see an increase of current load with V/Hz increase.
Frequency Converter 50Hz to 60Hz
2. Hz on a 60 Hz - The motor will turn approximately 20% faster and this will lead to some heat issue as cooling required more. The V/Hz will drop without any increase of current draw though. Since the increased of load, it good to check the motor Full load Ampreage (FLA) on the motor nameplate to make sure if there is a need to mitigate some of the load to avoid burn out.

Most of the issues on three phase can be mitigated however on single phase, you will have big issue. Since single phase motor required a start winding to provide the torque large enough to the motor start to spin. The start winding load normally is very large load that operate for a couple seconds.

A centrifugal switch is usually included on the rotor to control the power to the start winding. On a 60 Hz single phase motor, running at 50 Hz, the start switch could not reach the opening of the centrifugal switch since typical the switch opening speed set point is set around 80% running speed. Since the motor running 20 % slower, and it did not reach the switch speed, motor will burn out. Even with the start/run capacitors, it will reduce the effects of the capacitors which results in lower running and starting torques. This will cause the motor failed to start its load and will cause a burn out.

As for 50 Hz motor on a 60 Hz, the start speed will be reached faster 20% earlier than normal. When this occurred, the starting torque of the motor will be reduced. As it happened, the motor will failed to speed up and could be reach the normal speed. This could cause a burn out. However some of the single phase motors come with one or both start/run capacitors. When running 50 Hz on a 60 Hz, the capacitor effect will increase. This should be posing no problem.

In summary, on 3 phase motor, check the FLA to make sure it will not exceed the FLA. On the single phase motor, it will be wise to swap out the motor as it's cheaper to swap it out than having a burn out motor!

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