MCC bucket feeds VFD

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elec_eng

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Existing pump was used to be fed from combination stater with fuse disc in MCC. New pump will be controlled by a new VFD. Can I use the existing bucket to feed new VFD by just removing the OL and keeping the fuse?

I know you can’t t do this with the combination starter with MCP but since this is with the fuse not sure it can be done or not. Thanks.
 
Not an issue where the MCC OCPD is a fuse or a terminal magnetic breaker. It is only an issue where the OCPD is an instantaneous only device.
 
Take out the contactor too though. It's a bad idea to constantly power up a VFD by closing a contactor, it stresses the pre-charge circuit every time and will cause premature failure.
 
Jraef said:
Take out the contactor too though. It's a bad idea to constantly power up a VFD by closing a contactor, it stresses the pre-charge circuit every time and will cause premature failure.
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If the contractor is taken out, how is it going to be re-wired inside the bucket? Is there a retrofit kit or just splice and re-connect?

I assume there will be no listing issue, correct?
 
just take out the contactor and overload and feed the VFD from the fuse.

or even easier take out the wires from the fuse to the contactor and leave the contactor and overload in place. you can probably still feed the VFD from the fuse that way.
 
petersonra said:
just take out the contactor and overload and feed the VFD from the fuse.

or even easier take out the wires from the fuse to the contactor and leave the contactor and overload in place. you can probably still feed the VFD from the fuse that way.
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Thanks. So I take it there is no listing issue for doing this, correct? I thought somehow there was a listing for the motor controller.
 
elec_eng said:
Thanks. So I take it there is no listing issue for doing this, correct? I thought somehow there was a listing for the motor controller.
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Listing issue? Sure. But you already own it, it's yours to do with as you like now. Listing matters for two reasons:
1) The AHJ will want it when a new project is permitted and inspected. That becomes irrelevant once it's in.
2) Your insurance company may insist on it. That might be an issue if you ADDED something that was not listed, or re-purposed something for an unapproved use. But using a fused disconnect from a starter as... a fused disconnect? Not something anyone is going to get excited about. What you are doing is not violating any intended use of the product, as trying to use an MCP as a feeder would have for example..
 
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