Fuse project

[Doc_Bob]

I was asked to have a little demonstration on how fuses work. So, I wanted to have some car fuses "melt" as part of the demo. I want to demonstrate how the little metal link melts and the plastic housing stays intact. Now, how do I do it? Safely? Without starting a fire
Bob

 

[Jagmandave]

Just touch it to a car battery for a moment, it'll pop immediately!

 

[slowrev]

A variac transformer or variable power supply that will handle the current the fuse requires to blow, Plus about 30% with a load hooked up that will draw more current than the fuse can handle. A light bulb ? big power resistor, etc.
Hook an ammeter in series with the fuse so people can see how much current is going thru it, slowly crank up the voltage/.current and watch it blow.

 

[slowrev]

Umm, I always wondered how they test fuses to be sure they will blow at the proper amperage

statistical sampling I assume.

 

[jinman]

Use a very small amperage fuse and a 15 amp rated switch in series with the battery or jumper battery like Jagmandave suggested. Use big alligator clips on each end to attach to the battery terminals, and make sure the switch is open before connecting the clips. The switch will keep you from drawing an arc in the open when you short out the terminals. If you want to be super safe, use two fuses with one about 5 amps more than the other. You might also wire all this into a fuse holder, but a bunch of alligator clips always makes things look "dangerous."

 

[Doc_Bob]

A variac transformer or variable power supply that will handle the current the fuse requires to blow, Plus about 30% with a load hooked up that will draw more current than the fuse can handle. A light bulb ? big power resistor, etc.
Hook an ammeter in series with the fuse so people can see how much current is going thru it, slowly crank up the voltage/.current and watch it blow.

Wow! Where would I get a variac transfomer?????? Any brick and mortar shops have them??
Bob

 

[IH3444]

Got three of em, for lab use only......

 

[Doc_Bob]

Got three of em, for lab use only......

3?? Why do you need 3? I only need one
Bob

 

[IH3444]

Collected up over the years from other labs which had been disolved. One is out on loan now, so I guess I need to check on that one. Thanks for the remind. Are you going to post a picture of the poped fuse? Or better how about a mini video?

 

[mwechtal]

I was asked to have a little demonstration on how fuses work. So, I wanted to have some car fuses "melt" as part of the demo. I want to demonstrate how the little metal link melts and the plastic housing stays intact. Now, how do I do it? Safely? Without starting a fire
Bob

Bob,
From some ham radio sources, I've heard that the cheap no-name chinese fuses will sometimes melt and burn the plastic case, and the metal link is still intact. You might want to use Buss or Littlefuse brand fuses to be sure the fuse actually fuses!

Mike