VFD Noise

I would like to add a variable frequency drive to my C&P 10x15 OS. A large electric motor shop in the area recommended a Hitachi VFD and a Marathon inverter-duty motor. When I stopped by for a demonstration, the set-up squealed alarmingly, and the noise became more obnoxious as the frequency was reduced to 15-20hz, which is where I need it to be.

I hope this is not an inherent characteristic of VFD’s. Has anyone installed a VFD and inverter-duty motor that did not produce these noises? If so, please indicate the components used.

Many thanks for your help.

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2 thoughts.
1. I would suggest changing the pulley on the motor to a smaller size if possible, that allows the motor to run slightly faster with 2 benefits. Better cooling of motor and reduced noise.

2. You should be able to go into the parameters setup on the VFD and change the carrier frequency. with some testing you should be able to reduce the noise.

Post the model of VFD and I should be able to help you sort out the setup.



1. The motor pulley is 2”. Going smaller would probably not result in significant benefit. BTW, the steam pulley is 15”.

2. You are correct, increasing the carrier frequency is the solution to the noise problem. Technically, it doesn’t eliminate it but changes it to a very high frequency at low amplitude, thus inaudible, especially to my aging ears. Sometimes the motor must be derated when carrier frequency is increased a lot, but in this case that was not necessary.

I have a VFD, not sure what the motor is. No unexpected noises.

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