Thread: Fuses
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Old 22nd Mar 2014, 11:00 am   #41
Tubeglow
Retired Dormant Member
 
Join Date: Mar 2014
Location: Wolverhampton, West Midlands, UK.
Posts: 153
Default Re: Fuses

I haven't noticed this in the thread,

Looking at voltage ratings, think about HT+ on valve circuits etc.
The disconnection time is linked to the arc time within the fuse after the element breaks.
So things to think about are.

At fault current how much current can flow before the fuse disconnects.
What is the Arc distance and at what voltage of operation.

Then how is the arc quenched to increase the speed of operation.

So at fault, the fault draws as much current as the supply can deliver until initial element break. Then fault current will continue to flow until the gap (+ ionised gas) is big enough for the arc to stop.

So if you think about sand filled fuses as the element breaks the sand falls into the gap. If the element is under tension from a spring it will pull apart faster (arc distance) There is always more (if you have a DC fuse in a circuit you can use a cap)

Just a thought. If you use surge suppression for transformer magnetisation current you can fuse closer to the operation current of the circuit.

Just for fun.
Tubeglow.

Last edited by Tubeglow; 22nd Mar 2014 at 11:10 am.
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