I'm trying to select fuses for a 3 phase generator. It's a specialty generator and the manufacturer rates it at 360Vrms and 50Arms under full load. I'm fusing the 3 individual phases before they feed into a bridge rectifier. The rectifiers, 3 individual, are rated at 400A with a 50% duty cycle. The rectifier is also capable of absorbing a non recurring 3000A pulse for 8.3mS.
The voltage rating is easy, 600V standard size.
The current gets harder. The general rule of thumb is to oversize the fuse 125% from full load current. This gives us 62.5A rounded up to 70A. Then things get more complicated. The generator runs at 4kHz. That is not a typo it is 4kHz. Because of the high frequency and skin effect the fuse gets derated 0.8. This now makes the needed fuse 87.5A rounded up to 90A.
At that current and voltage all i'm finding are branch rated, current limiting fuses. These fuses are rated to interrupt 10000A or more and are the size of my forearm. I don't think i need branch rated fuses. The generator is a finite supply and i don't think that it's capable of achieving even a 1000A.
I would like to use a small fuses (space is kind of limited). Are there small, not branch rated fuses that i could use?