Fuses made from copper strip
Looking through my bits box for a few fuses and holders for a 40 Kw alternator I use for 3 phase in my workshop, I was looking for some over 50 amps in case anything went wrong with any of my machines. I found 3 which look about right but they are just a strip of copper 2 and a quarter inches long and half an inch wide clamped into a suitable holder. As a guess I would say they would probably blow at a bit over 50 amps. The thickness is, as far as I can measure it on my caliper is 1/32nd of an inch
Does any clever chap know how I can calculate the current capacity from these measurements and so adjust it by cutting the strip in half, for example. These 3 phases will be for fusing 3 separate 13 sockets but if I just put them in the lines they will also protect the outlet on 3 phase devices too. I suppose I could just hook an ammeter in line and a heavy duty variac, which I have and just wind it up till it blows, but I do not have an unlimited supply of the copper strips and it is not very scientific, is it? Anyone got a clue? Thanks George. |
Fuses made from copper strip
George wrote:
a strip of copper 2 and a quarter inches long and half an inch wide clamped into a suitable holder. As a guess I would say they would probably blow at a bit over 50 amps. The thickness is, as far as I can measure it on my caliper is 1/32nd of an inch Are the holders enclosed? sounds like a sizeable amount of copper to spray around if it goes pop ... Does any clever chap know how I can calculate the current capacity from these measurements and so adjust it by cutting the strip in half, for example. Anyone got a clue? Thanks George. As a starter, this calculator http://solderer.tv/wire-size-fuse-calculator reckons you need 0.42 mm^2 of copper for a 50A fuse, which sounds small to me, but would make your strip over 20x the required CSA. Another site seems to give same ball-park sizes, so maybe it's not to small http://www.powerstream.com/wire-fusing-currents.htm |
Fuses made from copper strip
George wrote:
Looking through my bits box for a few fuses and holders for a 40 Kw alternator I use for 3 phase in my workshop, I was looking for some over 50 amps in case anything went wrong with any of my machines. I found 3 which look about right but they are just a strip of copper 2 and a quarter inches long and half an inch wide clamped into a suitable holder. As a guess I would say they would probably blow at a bit over 50 amps. The thickness is, as far as I can measure it on my caliper is 1/32nd of an inch Does any clever chap know how I can calculate the current capacity from these measurements and so adjust it by cutting the strip in half, for example. These 3 phases will be for fusing 3 separate 13 sockets but if I just put them in the lines they will also protect the outlet on 3 phase devices too. I suppose I could just hook an ammeter in line and a heavy duty variac, which I have and just wind it up till it blows, but I do not have an unlimited supply of the copper strips and it is not very scientific, is it? Anyone got a clue? Thanks George. 50 amp fuse wire is 21 guage or.721mm dia or .412 sq mm the copper you have would be hundreds of amps. |
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