How useful are EMC fans and outlet filters for reducing EMC/EMI from VFD enclosures?

I am deciding on components for a bayed modular enclosure containing multiple VFDs (480V/350A/321Hp each) for a dynamometer. I am concerned given the high voltages and currents that EMI/EMC is going to be an issue for components and instruments outside the enclosure.

How useful are EMC fans and outlet filters for reducing EMC/EMI?

I am taking other steps such as shielded cables to the motors to try to reduce the EMC/EMI. My understanding is that wherever there is a cutout in the sheet metal of the enclosure you compromise the shielding. How much improvement does adding EMC fans and outlet filters help to retain the shielding? They are quite a bit more expensive than the non-EMC option.

EMC fans?

Are you thinking that “EMC filters” are air filters?

EMC filters are electrical devices that prevent electro-magnetic interference (EMI) created by the VFD from radiating through the wires to other devices, allowing the assembly to meet EMC (electromagnetic compatibility) requirements. It has nothing to do with fans or air filters. If someone is selling fans claiming they help meet EMC requirements, that sounds like a scam…

jraef said:

EMC fans?

Are you thinking that “EMC filters” are air filters?

EMC filters are electrical devices that prevent electro-magnetic interference (EMI) created by the VFD from radiating through the wires to other devices, allowing the assembly to meet EMC (electromagnetic compatibility) requirements. It has nothing to do with fans or air filters. If someone is selling fans claiming they help meet EMC requirements, that sounds like a scam…

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I am referring to fans and outlets not filter circuit elements/boxes. EMC fans typically have a conductive gasket all around them and also use filters that have conductive material in them or can at least dampen/shield electromagnetic waves. A number of enclosure and fan manufacturers sell them.

For example Rittal sells EMC fans.
https://www.rittal.com/com-en/products/PG0168KLIMA1/PGR1932KLIMA1/PG0201KLIMA1/PRO0300

https://docs.rs-online.com/234d/0900766b802cd6cd.pdf

Eldon
https://www.eldon.com/122570_EFE-en-EMC_Filter_fans.aspx

Pfannenberg
https://www.pfannenberg.com/en/thermal-management/filterfans/emc-filterfans/

Others do also.

designvfds said:

I am referring to fans and outlets not filter circuit elements/boxes. EMC fans typically have a conductive gasket all around them and also use filters that have conductive material in them or can at least dampen/shield electromagnetic waves. A number of enclosure and fan manufacturers sell them.

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Surely, they offer a measurable difference, or there wouldn't be a market for them. The question is whether your particular application requires such a high level of shielding. I think that using the EMC fans and filters would be overkill in many (if not most) industrial environments. I don't know what the "components and instruments outside the enclosure" consists of in your application.

If you do require the maximum available shielding, then an enclosure air conditioner would probably be your best bet, although it would be even more expensive.

designvfds said:

I am taking other steps such as shielded cables to the motors to try to reduce the EMC/EMI.

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So, from this we can conclude that the motor cables are not yet shielded. It will make a big difference to switch to shielded cables.
Other steps are using inlet filters, output filters (especially for longer cables), and being vigilant about shielding and terminating the shields on large earth bus-bars with a clamp with a large surface for the shield to contact to.
The shield must go all the way to the VFD; not cut at the entry to the panel.
And the earth must be good.

Never heard about EMC fans before. Learned something new.
I think that must be for extra high requirements. Like in sensitive laboratory environments.

Fan does not have anything with reducing EMC. Only thing that helps is gasket.
https://ph.parker.com/us/en/emi-shielding-gaskets

When somebody makes the opening in the cubicle he disrupts faraday cage. EMI gaskets are here to help, but if you have metal grill/filter, you do not need EMI gaskets (if you install it adequately).

goghie said:

Fan does not have anything with reducing EMC. Only thing that helps is gasket.
https://ph.parker.com/us/en/emi-shielding-gaskets

When somebody makes the opening in the cubicle he disrupts faraday cage. EMI gaskets are here to help, but if you have metal grill/filter, you do not need EMI gaskets (if you install it adequately).

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The fan and filter kits we used back in the day were typically made of metal, but they are typically made of plastic these days.

What is the input voltage to the drive?
how far is it from the vfd to the motor?
vfd size?
motor hp?
regards,
james