The Hypertherm 1000 manual states to use a slow blow fuse. I spoke with their tech support and they recommended a 60A slow blow fuse. I currently have a 100A disconnect switch with class H fuses to run my Tig welder. I have a 60A box that accepts Class H, K5 style fuses which I am connecting after my 100A switch. I was going to run the standard off the shelf 60A NON class K5 style fuse. Will this be a problem? Or do I absolutely need this slow blow fuse which I can't seem to find anywhere. Are slow blow the same thing as Time Delay fuses?

So what do others run for thier 60A plasma cutters?

Thanks.

Are slow blow the same thing as Time Delay fuses?


Yes, they are.

Thanks!

Has anyone used a non time delay fuse with the plasma cutters? I'm guessing the plasma cutters have a surge current that may blow a standard fuse. Though I don't know how thick of material I would need to cut to reach a 60A load.

Sometimes it is the "power on" inrush current the one that blows fast fuses, many of the new inverter type equipment charges directly a bank of capacitors from the line (1 or 3 phase) through a bridge rectifier. This initial charging current can blow the non "time delay" fuses.

The surge is limited when the manufacturer uses a current limiting resistor in series with the rectifiers which is bypassed by a relay when certain voltage is reached at the capacitor bank or after a time delay.

Better designed equipment will have a soft-start controlled rectifier circuit or Power factor correction circuit which control the surge current.

I found some 50A time delay fuses to fit my box. I went with the 50A since my receptacle is rated at 50A. Unless I am cutting 1" thick steel all day long, I don't think I should have a problem.

Thanks for the info.

Time delay is the same thing as slow-blow. They are available at any electrical supply house, but you probably won't find them at a hardware store or lumber yard like Lowes or Home Depot.