Reducing Fault Current

[Jay Cantu]

The utility is feeding a site with (6) 2000kVA transformers which are paralleled together. Transformer Voltages are 13.2kV/277V-480V, %Z=6.02%. The switchgear downstream of the transformers are rated at 200kAIC.
I want to install a piece of equipment which has a main breaker that is rated at only 65kAIC.
The fault current at the equipment location has been calculated to be 150kAIC.

We are thinking about inserting a current limiting or semiconductor type fuse ahead of the equipment.

What would you reccommend?

 

[jim dungar]

We are thinking about inserting a current limiting or semiconductor type fuse ahead of the equipment.

I never consider a semiconductor type fuse as being current limiting for anything other than semiconductors.

In my opinion, if you want to lower the fault current to your breaker you need to add impedance.

I assume you have looked into available series ratings?