UL489 VS UL508: VFD DRIVEN MOTOR

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fifty60

fifty60

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I have a VFD powered motor. The contactor I am using to bring 480V power to the line side of the VFD has an SCCR of 5KA, unless used with an approved circuit breaker combination.

All of the circuit breaker combinations, however, are UL508 CB's. If I use a UL 489 breaker instead, my SCCR will be 5KA. I need to use a UL 508 breaker to increase the SCCR. Can I use a UL 508 breaker on a motor load if a VFD is on the same branch circuit?

I know if the VFD was not there, then I could use a UL489 or UL508 breaker, but with the VFD am I limited to just the UL 489 breaker at that point?
 
fifty60 said:
I have a VFD powered motor. The contactor I am using to bring 480V power to the line side of the VFD has an SCCR of 5KA, unless used with an approved circuit breaker combination.

All of the circuit breaker combinations, however, are UL508 CB's. If I use a UL 489 breaker instead, my SCCR will be 5KA. I need to use a UL 508 breaker to increase the SCCR. Can I use a UL 508 breaker on a motor load if a VFD is on the same branch circuit?

I know if the VFD was not there, then I could use a UL489 or UL508 breaker, but with the VFD am I limited to just the UL 489 breaker at that point?
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I think you may be mixing up the UL standards and mistaking UL 508 for UL 1077.

You can either use a UL 489 or UL 1077 breaker for this application. You can use a UL 489 breaker anywhere, but you cannot substitute a UL 489 breaker with a UL 1077 breaker.

The UL 508 listing will be required for an assembly of products, each with different listings.Basically, if you piece together an OCPD combo and enclosure it needs to be fabricated by a UL 508 recognized shop.

So... You can use a UL 489 or UL 1077 breaker within the VFD enclosure for motor protection, a UL 489 breaker in the source panel (or outside the VFD enclosure), and if you custom build any breaker enclosures or combo's the assembly would need to be listed to UL 508. Please note that VFD assemblies fall under UL 508C.
 
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Yes that is confusing me as well. I am pulling this from Allen Bradleys online SCCR tool, which I believe they have recently revamped. They list their 140M breakers as "UL 508 Manual "Type F" Self-Protected CMC", and say they are not UL489.....not sure what it means, and if they have mislabeled them, but I believe they are only intended for motor loads..
 
fifty60 said:
Yes that is confusing me as well. I am pulling this from Allen Bradleys online SCCR tool, which I believe they have recently revamped. They list their 140M breakers as "UL 508 Manual "Type F" Self-Protected CMC", and say they are not UL489.....not sure what it means, and if they have mislabeled them, but I believe they are only intended for motor loads..
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This must be a small VFDs then.

When a VFD manufacturer needs to submit a device for an SCCR in series combination, they do so at their own expense and it's around $25k per line item. So to help recoup some of the costs of that process, the mfrs tend to want to get the approvals using their own components, not those of a competitor. In the case of A-B, they used to brand-label their UL489 circuit breakers from Eaton, so to list their smaller drives with an Eaton breaker meant they were indirectly benefiting Eaton. So on the smaller drives, they did their SCCR series listings using their own Bul. 140M Motor Protective Circuit Breakers (MPCB) that are UL508 listed. This devices are listed for 65kAIC stand-alone (so long as there is a max. 1200A breaker or fuse up stream somewhere), which is far far less expensive than a 65kAIC listed UL489 breaker. This is only the case up to about 25HP on the PowerFlex 520 series and I think the PF4s and PF40s. A-B now has their own brand of UL489 listed breakers and all of their larger drives have been re-listed with them, but on the smaller ones, most people like using those IEC style MPCB devices anyway because they are smaller and less expensive, so they have not re-listed those with the UL489 breakers.
 
jeremy.zinkofsky said:
I think you may be mixing up the UL standards and mistaking UL 508 for UL 1077.

You can either use a UL 489 or UL 1077 breaker for this application. You can use a UL 489 breaker anywhere, but you cannot substitute a UL 489 breaker with a UL 1077 breaker.

The UL 508 listing will be required for an assembly of products, each with different listings.Basically, if you piece together an OCPD combo and enclosure it needs to be fabricated by a UL 508 recognized shop.

So... You can use a UL 489 or UL 1077 breaker within the VFD enclosure for motor protection, a UL 489 breaker in the source panel (or outside the VFD enclosure), and if you custom build any breaker enclosures or combo's the assembly would need to be listed to UL 508. Please note that VFD assemblies fall under UL 508C.
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UL508a is for listed control panels. UL 508 is for certain industrial control components. They are not the same thing.
 
fifty60 said:
Would you expect the ul 508 breaker to also be either ul 489 or ul 1077?
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No. Different standards, different applications. UL489 would mean that the breaker can stand completely alone in a circuit as a feeder OR a branch circuit protective device. UL508 would be applicable only as a branch circuit protective device for a motor, meaning it must be coordinated with another feeder device upstream. UL1077 is only useful as a “supplementary” protective device behind a branch circuit protective device that is UL489 or a UL listed branch rated fuse.

UL1077 is almost useless from a Code standpoint, you only use them when YOU want protection above and beyond what the code requires. For example you have a device rated for 3A, but the smallest UL489 breaker is 10A, you can use the 10A breaker as the branch, then add a 3A 1077 rated breaker down stream of it. Most people who buy (and sell) those things don’t fully understand it and misapply them, then get burned by an inspector (assuming the inspector fully understands).
 
What do you think about the UL508 breaker on a motor circuit that includes a VFD? The 508 breaker would be the only breaker upstream of the VFD and Motor..
 
fifty60 said:
What do you think about the UL508 breaker on a motor circuit that includes a VFD? The 508 breaker would be the only breaker upstream of the VFD and Motor..
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Only breaker? You mean it is the Service Entrance? Then no, it’s not SUSE. But if there is an SUSE breaker or fuse 1200A or under somewhere ahead of it, then it’s OK.
 
Would a 35A UL 489 breaker upstream of the UL508 breaker make make the UL 508 breaker permissible to be used on a non motor load? In this instance it is a VFD load...
 
fifty60 said:
Would a 35A UL 489 breaker upstream of the UL508 breaker make make the UL 508 breaker permissible to be used on a non motor load? In this instance it is a VFD load...
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If the VFD is series listed with the device, then yes. But it’s not something you can do on your own in the field, they must be listed together by the mfr.
 
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