OT: Short circuit rating confusion

Hi,

I use Allen Bradleys 194e serie as load switch for my cabinets. The technical data confuses me, it says:

On the general data it says:
Short-Circuit Ratings 5 kA

On electrical rating it says:
Short circuit current (co-ordination type 2) Rated conditional short-circuit current
This vary depending on the size of the breaker. from 15-30kA

How to interpret this?

https://literature.rockwellautomation.com/idc/groups/literature/documents/td/194-td002_-en-p.pdf

If you aren't sure what Type 2 coordination is, take a look here:

https://www.schneider-electric.us/en/faqs/FA105974/

Basically, what the chart is telling you is what maximum amperage general purpose fuse you can use in combination with each size switch and still achieve the high fault current rating listed in the table.

As an example, assume you are using a 32A rated switch. According to the table, as long as the circuit is protected with a 35A or lower fuse the short circuit rating of the switch is 15kA. If you had a 40A fuse protecting the circuit the short circuit rating would drop to 5kA.

Keith

Ah ok so that's how to interpret it, thanks alot it makes sense now.

Also note that the first value, SC rating = 5kA, is per UL rules.
The "Short circuit current (co-ordination type 2)" is an IEC rating, and it is only in series with fuses, specifically type g or G.

This is going to be the same for all non-fused switches of this type. They are made to go near the motor as a safety disconnect / isolator, but must be used in coordination with some other upstream Short Circuit Protective Device that limits the fault current.

Thanks for clarification, it doesn't clearly state that to 5kA is UL. Tricky with both UL and IEC in the specs.


I have another issue with a 100-c contactor. If I interpret this correct then if I fuse a 100-c16 contactor with max 50A gG fuse then it can handle 50kA type 1? The headline says fuse or circuit breaker rating but the options are only fuses.
Page 54 https://www.google.com/url?sa=t&sou...FjAAegQIBBAC&usg=AOvVaw1tvhRcF3rKg8EWvT5mKsLU

Also this fuse will be before the whole cabinet in the supply end but I guess that doesnt matter then , what matter is that the fuse is correct size

I read the chart the same way. For a 100-C16 contactor you could have up to a 50A gG class fuse and still have a type 1 coordination short circuit current of 50kA for IEC purposes.

Keith

Good to hear that I'm not alone thanks for your time