MV Fuses

[faresos]

Can 15.5KV rated fuses be used in 4.16KV system? The client directed us to provide 15KV equipment and cables but to size all equipment ampacity to 4.16KV. The facility initially will utilize 4.16KV system then the service will change in the future to 12.47KV once becomes available.

Thanks,

 

[ron]

We use 600V fuses in 120, 208, 277 and 480V applications all of the time

 

[faresos]

We use 600V fuses in 120, 208, 277 and 480V applications all of the time

I agree and that's what I know but wondering if will be the same for medium voltage system.

 

[drktmplr12]

I agree and that's what I know but wondering if will be the same for medium voltage system.

MV fuses are simple in application but not design, you should consult with the manufacturers for clarifications and get them to tell you it's okay.

further, pay attention to 110.34 because there are different working distance clearances for the two voltages.

somewhat unrelated, but an interesting video deconstructing a 7.2 kv fuse

 

[Jraef]

Often times, MV fuses are used in the listing of other devices in the power structure. So if you have 5kV gear, it will have been tested and listed with 5kV fuses. If you substitute a 15kV fuse, the gear was not likely tested and listed with those devices. This is especially true of "controllers", like motor starters, where they must have a "Class E-2" rating as a complete assembly. Class E-2 means that the controller RELIES on the fuses to clear faults that are in excess of the controller's (contactor's) ability to interrupt it.

But if you are using 15kV rated gear and putting 4160V through it, I don't think that would be an issue.