How a big HRC Fuse is made..

[Gavin John Hyde]

You aren't likely to see one of these everyday of the week but it is quite an interesting video i just saw, We are childminding tonight and my nephew is on a how its made binge on the youtube app on the tv... Didnt realise they had a firing pin in them mind!

 

[UKMeterman]

These are HV fuses for fitting into 11KV ring main units.

 

[sparkdog]

Be a struggle getting that into a 13A plug.

 

[freddo]

I have a similar one of those in my kitchen, it's not fitted with a striker. 63A 12KV. It's much heavier than it looks.

 

[PEG]

Be a struggle getting that into a 13A plug.

All that would take,is a farmer,with a 240V compressor,a tractor with a flat tyre,and one blown standard fuse....and in it would go

 

[PEG]

Be a struggle getting that into a 13A plug.

All that would take,is a farmer,with a 240V compressor,a tractor with a flat tyre,and one blown standard fuse....and in it would go

 

[I2C]

You aren't likely to see one of these everyday of the week but it is quite an interesting video i just saw, We are childminding tonight and my nephew is on a how its made binge on the youtube app on the tv... Didnt realise they had a firing pin in them mind!

Agree with previous comments, these are for use with HV (High-Voltage).

Why do they contain an explosive-charge?
Put simply, high-voltages can jump through the air (like a police taser for example) and higher-voltages will jump considerably further than lower-voltages; the result is referred to as an 'arc / arcing'.

The problem is that arcing creates very-high temperatures, especially in the area that the arc starts & finishes, which can easily melt metal (basically how welding works). The heat is therefore perfectly capable of damaging electrical conductors during disconnection, and must be avoided.

With this said, explosive-disconnection-fuses are made for use in HV conductors and designed to detonate a small charge during fault-conditions, causing the conductors to separate very-quickly in order to prevent damaging-arcs.

 

[I2C]

This is a three-phase fuse which is installed on each of the individual phases. It's imperative that all phases simultaneously disconnect, opposed to a singular phase. The "firing-pin" is used to trigger the disconnection of the other phases during a fault to ensure safety.

 

[1Justin]

Likewise.. And I had no idea they would be wound on a spiral like that either. I can guess that compared to a straight element ( which I'd have expected), the spiral adds length so presumably reduces the relative heat-loss conducted out the ends in the event of a small overload.

 

[UKMeterman]

This is a three-phase fuse which is installed on each of the individual phases. It's imperative that all phases simultaneously disconnect, opposed to a singular phase. The "firing-pin" is used to trigger the disconnection of the other phases during a fault to ensure safety.

Yes the firing pin hits the trip trigger for the contacts in the ring main unit so the other phases are also disconnected.

 

[Percyprod]

It will only be about 25 amp