Chiller SCC Calc, or Why Is This Even a Thing?

[JoeStillman]

There is such a mismatch between the size fuse I need and the SCCR that the SCCR is way below the current limiting threshold. CLFS of a smaller rating - say 200 amps - can limit you to under 5k. But this monster takes a 450 A fuse.

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[Sahib]

Suppose the available short circuit current is okay. Talk to fuse manufacturers for a parallel combination of CLF's such that it is rated for 450A and its current limiting is less than 5K. I think it is possible to select such a combination from the list of fuse ratings and so it is easy for a fuse manufacturer to offer it after factory testing.

 

[JoeStillman]

Suppose the available short circuit current is okay. Talk to fuse manufacturers for a parallel combination of CLF's such that it is rated for 450A and its current limiting is less than 5K. I think it is possible to select such a combination from the list of fuse ratings and so it is easy for a fuse manufacturer to offer it after factory testing.

I never heard of paralleling fuses. Are any switches made with parallel fuse-holders?

 

[iwire]

I never heard of paralleling fuses.

Likely because it is a code violation anyway.

240.8 Fuses or Circuit Breakers in Parallel. Fuses and
circuit breakers shall be permitted to be connected in parallel
where they are factory assembled in parallel and listed
as a unit. Individual fuses, circuit breakers, or combinations
thereof shall not otherwise be connected in parallel.

 

[JoeStillman]

Final Follow Up

Final Follow Up

Thank you to everyone who looked over my rant. Kicking it around on here gave me confidence to debate with the chiller manufacturer.

Today they offered to upgrade the SCCR for no charge as if it were modified at the factory. There will be no impact on the warranty. I asked if this upgrade was because nobody disagreed with the letter I wrote. Crickets.

I think we all learned something here today.

 

[mgookin]

Thank you to everyone who looked over my rant. Kicking it around on here gave me confidence to debate with the chiller manufacturer.

Today they offered to upgrade the SCCR for no charge as if it were modified at the factory. There will be no impact on the warranty. I asked if this upgrade was because nobody disagreed with the letter I wrote. Crickets.

I think we all learned something here today.

+100

 

[Sahib]

The manufacturer might be an amicable person.

Providing an equipment with low SCCR in a super strong grid and protecting it with a CLF in addition to expulsion fuse is a common occurence in utilities......................