EMI/RFI testing large motors

[Designer69]

Gents,

I am not sure if large motors (8000 HP 13.8KV) are usually tested for EMI/RFI emissions. I thought usually only digital equipment is tested such as controllers etc. Some people here at work are suggesting that we also test these new large motors. What is your opinion?

Thank You

 

[Designer69]

bump bump bump

 

[dkarst]

Since nobody else has hopped in yet... I don't have much experience here but will try. The reason the controllers have to be tested for emissions is they are the same as a PC, an unintentional radiator of RF that can interfere with other devices such as broadcast radio or TV. These are governed in the US by FCC part 15 and similar regulations in other parts of the world. Class A is generally required for commercial applications and Class B for home. If I remember one of the requirements is a digital clock frequency of some low amount.

I cannot state with certainty, but I don't think your large motor would fall into being regulated by this. There are other aspects of electromagnetic compatibility that you may want to worry about just as good design practices, such as power line disturbances when starting your motor. Hope someone else drops by to help you out.

 

[rcwilson]

The field brushes or the rotating diodes in a brushless exciter circuit on a synchronous motor can generate some EMI. Military specs require testing teh exciters on generators and synchronous motors to prevent interference with communications and control devices.

At 8,000 HP, I'm guessing these are synchronous.

Check with the motor supplier and do the test in the factory. It is expensive to do in the field and the background interference from radios and other transmittters that makes getting good readings difficult.

 

[mbeatty]

I cannot state with certainty, but I don't think your large motor would fall into being regulated by this. There are other aspects of electromagnetic compatibility that you may want to worry about just as good design practices, such as power line disturbances when starting your motor. Hope someone else drops by to help you out.

For CE Mark (European), we have been required to have our compressor packages tested for electromagnetic compatibility (EMC) and for RF emissions.
Regards,
Mark