malachi constant
Senior Member
- Location
- Minneapolis
See here for original thread:
http://forums.mikeholt.com/showthread.php?t=163026
Short version: two 208V ~300A chillers were installed with control enclosures rated 5kAIC. Actual available ISC is greater than 5k. Inspector flagged it, it was a new one for me and a lesson learned that won't happen again. That said have to fix it.
The manufacturer is providing parts and installation to field modify the two chiller controls enclosure with parts that will result in a 65kAIC rating. They need the Owner (who I am consulting to) to line up:
1. An electrician to disconnect/reconnect at the lugs (easy enough).
2. An inspector to field inspect that the new installation meets UL standards equipment.
It is the second one that I am having trouble with. I have not been able to talk directly with the factory to see what UL listing we are trying achieve, and the local "engineering inspectors" I talk to seem unsure what I am asking. I am trying to get contact information for someone within the factory but until that occurs I would appreciate any insight this community has to offer.
FYI - we have dismissed adding impedance as I understand that option to entail either adding hundreds of feet of coiled-up wire (expensive and impractical) or a 208V:208V transformer (also expensive - would need to be (2) 112kVA transformers, (2) 400A disconnects, 60' of above-grade 300A feeders, everything weatherproof, and none of it would fit inside the tidy new chiller enclosure we constructed). I suppose it is possible when all the costs are added up we could end up with the chiller being an option, but it would run about ~$50K, so I'm pursuing the above-mentioned factory fix above until I find out what those costs are.
If there is another solution I'm all ears. Someone in the above thread mentioned a line reactor, which I am not familiar with. Is it relatively small and cheap? I think of it as a medium voltage component - can it be added to a 208V system? Not sure how to model added impedance in SKM either - right now I've got 27kA available and need to get down to 5kA. (Also: I did quite a bit of research and couldn't find an appropriate fuse that would come close to limiting to that amount.)
Any and all thoughts are appreciated!
http://forums.mikeholt.com/showthread.php?t=163026
Short version: two 208V ~300A chillers were installed with control enclosures rated 5kAIC. Actual available ISC is greater than 5k. Inspector flagged it, it was a new one for me and a lesson learned that won't happen again. That said have to fix it.
The manufacturer is providing parts and installation to field modify the two chiller controls enclosure with parts that will result in a 65kAIC rating. They need the Owner (who I am consulting to) to line up:
1. An electrician to disconnect/reconnect at the lugs (easy enough).
2. An inspector to field inspect that the new installation meets UL standards equipment.
It is the second one that I am having trouble with. I have not been able to talk directly with the factory to see what UL listing we are trying achieve, and the local "engineering inspectors" I talk to seem unsure what I am asking. I am trying to get contact information for someone within the factory but until that occurs I would appreciate any insight this community has to offer.
FYI - we have dismissed adding impedance as I understand that option to entail either adding hundreds of feet of coiled-up wire (expensive and impractical) or a 208V:208V transformer (also expensive - would need to be (2) 112kVA transformers, (2) 400A disconnects, 60' of above-grade 300A feeders, everything weatherproof, and none of it would fit inside the tidy new chiller enclosure we constructed). I suppose it is possible when all the costs are added up we could end up with the chiller being an option, but it would run about ~$50K, so I'm pursuing the above-mentioned factory fix above until I find out what those costs are.
If there is another solution I'm all ears. Someone in the above thread mentioned a line reactor, which I am not familiar with. Is it relatively small and cheap? I think of it as a medium voltage component - can it be added to a 208V system? Not sure how to model added impedance in SKM either - right now I've got 27kA available and need to get down to 5kA. (Also: I did quite a bit of research and couldn't find an appropriate fuse that would come close to limiting to that amount.)
Any and all thoughts are appreciated!
