When testing a switch for switching we use a specially designed transformer, which delivers the desired voltage and current for the switching duration only. The current is of the order of 1200A and the voltage 3600to 4000V. The duration is less than 60 millisecs.
We use a fuse of 12 kV 80 A nearest to the switch to avoid the tripping of the breaker in case the switch fails for some reason by having the arc extended resulting in short circuit, which has happened some times. The fuse works well. But is very expensive.
We want to use a fuse that is rewire able.
The fuse should maintain the value of test current during the 60 millisecs of test duration.
The fuse should blow when the current exceeds 1500A in 100 mil sec.
I have the following idea to construct our own fuseand request critical inputs.
There are 2 bus bars upper and lower.
The lower bus is rigidly fixed. This is the output.
The upper bus,the input, is movable up and down and is guided well in a insulated frame.
The fuse connects the two bus bars.
The upper bus is held by a spring attached to a top member of the guide frame.
The fuse is held taut by the spring force.
When the fuse blows the spring will pull the top bus up and away from its original position.
The spring force will be adequate to give a withdrawing velocity of 2 m/sec.
This whole thing will be in a strong box for protecting people.
The box can be filled with quartz sand.
What are your thoughts against this model?
What will be an appropriate material for the fuse element?
Any suggestions for design of the fuse strip or a wire (what dia) will suffice?