How to detect if a high voltage fuse is blown

Question

I have a 150A fuse on a 100A @ 400V nominal battery pack. There are 5 service relays and 2 isolation relays (one on each pole) in this battery pack. I'd like to make sure that none of these relays can be opened if the fuse is blown (so some kind of interlock would be wired in series with the emergency stop buttons, and the fuse blowing would trigger the same re-startup routine).

What's the best way to do this, or is there a type of fuse with an interlock which can be used?

I must not make an electrical connection between the pack and the interlock/fuse checking circuit.

Answer 1

You can buy a lot of larger values of fuses with blown fuse indicators, and a microswitch that opens when the fuse blows. I haven't used them on 150A fuses (I've used them on 800A+ Semiconductor Fuses), but they should be around.