What I've got is a purely resistive three phase load protected by fast acting fuses. The total load is 250kW, but each leg is only seeing 310A maximum. I typically rate my fuses 125% high to avoid nuisance trips, which is why I'm using a 400A fuse.
This cabinet is getting hotter than usual, though, at about 80°C (176°F). I believe this is the root cause of my trips. Adding fans to cool the cabinet is a cost prohibitive fix. I plan to replace the 400A fuse with a 450A fuse, but I want to make sure that I'm still "safe" if I do that.
Is there a rule of thumb guide for sizing fuses in higher ambient temperatures?
This cabinet is getting hotter than usual, though, at about 80°C (176°F). I believe this is the root cause of my trips. Adding fans to cool the cabinet is a cost prohibitive fix. I plan to replace the 400A fuse with a 450A fuse, but I want to make sure that I'm still "safe" if I do that.
Is there a rule of thumb guide for sizing fuses in higher ambient temperatures?