Fusible Disconnect on VFD

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Besoeker

Senior Member
Location
UK
Is there any issue with using a fusible disconnect to feed a VFD?

Thanks for any response.
We routinely fit fuse switches at the input of the VFDs we do.
Quite often it's a requirement specified by the customer.
So technically,it isn't a problem. I don't know if there are any local regulations that it might contravene.
 

tom baker

First Chief Moderator
Staff member
Do you mean is in if one fuse blows the VFD could single phase? Not an issue with VFDs, and not an issue with motors if the fuse is sized correctly and is a dual element time delay type fuse. I have had motor damage on MCP but never on fuses.
Mfgs will allow fused or circuit breaker motor branch ciruit short circuit and ground fault protection. IMO fuses are better, some mfgs will acknowledge that if you ask, but they don't restrict it.
However if you are going to use fuses, there often is a specific type required, usually a type J. My integrator who builds my VFD panels uses type J fuses. Just keep spares on hand as they are often non stock locally.
 
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