VFD fused Disconnect

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Is there a feeder breaker somewhere ahead of them?

The reason I ask is because you can use the less expensive "UL508" style fused disconnects in something like a fiberglass 4X box, but those cannot be used as a FEEDER, only a BRANCH disconnect. You need a UL98 listed fused disconnect or a UL489 listed circuit breaker upstream of it somewhere. So if you have a breaker in a panel that is already dedicated to this circuit, you are good to go with those lower cost disconnect switches.
 
Jraef said:
Is there a feeder breaker somewhere ahead of them?

The reason I ask is because you can use the less expensive "UL508" style fused disconnects in something like a fiberglass 4X box, but those cannot be used as a FEEDER, only a BRANCH disconnect. You need a UL98 listed fused disconnect or a UL489 listed circuit breaker upstream of it somewhere. So if you have a breaker in a panel that is already dedicated to this circuit, you are good to go with those lower cost disconnect switches.
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There are 24 fans split up on 4 feeders that we will tap. I looked at the 508 but hadn’t researched yet. Thanks
 
ptonsparky said:
A fused switch I'm looking at has an ability to be operated with a thru the box side mount handle. Is the enclosure door required to be interlocked mechanically so it cannot be opened with the switch in the ON position? Normally I would go through the door.
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NFPA 79 would require it, but the question will be if NFPA 79 applies at all to your situation.
 
ptonsparky said:
Well, it is not Industrial Machinery, nor is the location.
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Then there is nothing really in the NEC that requires it. OSHA in general requires that electrical equipment must be provided with a means of controlling access to only qualified personnel, but a simple padlock would suffice for that.

I'm thinking though that UL 508 might require a door interlock though. Are you sure that the ones you are looking at are UL 508 listed?
 
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When we do fans in dairy barns, standard procedure for us, is AB manual motor protectors in AB plastic rotary disconnect enclosures.

I've never used fused disconnects for this.
 
ptonsparky said:
These fans all have Lenze VFDs needing 10 amp protection. I would be very happy with manual motor protectors if that is doable.
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Are you using those Lenze 4X drives with an integral rotary disconnect and ethernet/wifi capabilities?

In the last 2 years we've installed almost 140 of those Lenze 4X VFD's in two different dairies.

The electrical engineer for the project had us put these VFD's/fans on 30 amp circuits with a handful of VFD's on each circuit. No supplemental protection installed, even though I HIGHLY recommended individual OCPD so one bad drive will not take down the whole string.

To date, they've had no less than 8 VFD's fail in less than two years, tripping the breaker and of course, killing power to the rest on the circuit.:happyno:

I have not personally replaced any myself, I've had the guys do it, but I'm told the failures they're seeing are burns/scorch marks right at the 480v terminals with the internal drive wiring.

The really silly part is, shutting the integral disconnect off does not take the damaged drive out of the system allowing the others to run, as the problem is the internal factory wiring on the line side of the disconnect.

Fortunately, we did not supply the drives so the repair costs are on someone else.

They did not like my price for supplemental protection with manual motor protectors, I'm hoping you have better luck than I did with your customer.
 
Cow said:
Are you using those Lenze 4X drives with an integral rotary disconnect and ethernet/wifi capabilities?

In the last 2 years we've installed almost 140 of those Lenze 4X VFD's in two different dairies.

The electrical engineer for the project had us put these VFD's/fans on 30 amp circuits with a handful of VFD's on each circuit. No supplemental protection installed, even though I HIGHLY recommended individual OCPD so one bad drive will not take down the whole string.

To date, they've had no less than 8 VFD's fail in less than two years, tripping the breaker and of course, killing power to the rest on the circuit.:happyno:

I have not personally replaced any myself, I've had the guys do it, but I'm told the failures they're seeing are burns/scorch marks right at the 480v terminals with the internal drive wiring.

The really silly part is, shutting the integral disconnect off does not take the damaged drive out of the system allowing the others to run, as the problem is the internal factory wiring on the line side of the disconnect.

Fortunately, we did not supply the drives so the repair costs are on someone else.

They did not like my price for supplemental protection with manual motor protectors, I'm hoping you have better luck than I did with your customer.
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VERY nice to know. I wasn't going to give them a choice about supplemental protection. I thought about the disconnects but sort of discarded that one. Now I know it's gone.

Other than the failures is their control working decently?
 
Jraef said:
Then there is nothing really in the NEC that requires it. OSHA in general requires that electrical equipment must be provided with a means of controlling access to only qualified personnel, but a simple padlock would suffice for that.

I'm thinking though that UL 508 might require a door interlock though. Are you sure that the ones you are looking at are UL 508 listed?
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No, they are UL98 switches, fused. Thinking of putting them in an enclosure myself. I would rather not but that extra $28,000 is close to a budget breaker.
 
ptonsparky said:
VERY nice to know. I wasn't going to give them a choice about supplemental protection. I thought about the disconnects but sort of discarded that one. Now I know it's gone.

Other than the failures is their control working decently?
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The first dairy with 70 VFD's was done with hardwired ethernet cabling. We burned through a lot of shielded Cat5 for 70 fans. It was expensive.

The second dairy with the other 70, they were able to get wireless drives or purchase a wifi adapter, I'm not sure exactly, we didn't supply them. It was a lot simpler for us with the wifi and a few antennas than the hardwired 70 on the first dairy.

We don't do the automation for these, just run the conduit and pull the cables for the guys that do.

As far as I know, they are working fine.

It's just them blowing up that's been a pain for us. They are all in the holding pen and parlor areas, so replacement takes two guys and some coordination just to deal with the cows.
 
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