What the heck?

Does this fuse have a diode in it? If not, why did they paint a diode on it? Why would you put a diode in a fuse? I'm so con-fused!

It's an indication that the fuse is a semiconductor fuse. Very high speed, intended to protect semiconductors from fault currents.

Keith

That's kind of what I was thinking, but I don't like to make assumptions. Thanks for the reply!

That's correct; it's just an indication that it's a semiconductor protection fuse.

From a Bussman catalog:

It means it only clears a fault when the current flows in that direction, so only on half of each sine wave....


JK:beerchug:


By the way, I love the concept of "protecting" semiconductor devices... In a typical power application for semiconductor devices such as VFDs and Soft Starters, where these are used a lot, the only way to HAVE a fault that would clear the fuse if if the semiconductor device has ALREADY failed! So now you not only have to replace the semiconductor device, you also have to buy another VERY expensive fuse... Brilliant marketing concept on the part of the fuse manufacturers.

Actually this particular drive has blown one or more these fuses in the past without the semiconductors failing, apparently, as all 3 fuses were different. I actually replaced this 50 amp fuse with a 40 amp fuse, and was able to return it to service. The new 50 amp fuses will be here today, and I will replace them all.