FUSE BREAKING CAPACITY ELECTRICAL QUESTION|Online electrical engineering & Electrical Interview Questions

Tuesday, August 13, 2013


Here is another question related to electrical fuse from one of our follower.The question goes like this.
I face problem it really makes me confused about section of MV fuse.We have a 6MW, 24 kv project we need a disconnect fuse type switch.I calculate the fusion rate: 200 Amps.
When I refer to fuse catalog I found the fuse rate as below:Rated voltage = 24 Kv,
Rated current= 200 A,  Breaking current= 840 A. I do not understand what is that 840 A, what this mean any body could help me about that?

Fuse is a device that is made of low resistance material which is used to protect the electrical devices from the high current surges.Rated current is the the current at which the fuse is rated for.Breaking current is the current at which the fuse breaks.When the fuse breaks it breaks by giving out spark.

In practical classes, while doing armature control or field control of DC motor you would have seen breaking of fuse by giving out spark and a big sound.Also in house, some times we would have seen the fuse breaks.Then we take out the fuse carrier and replace it with the new fuse wire and put it in place.

Imagine without these fuses the high current would have damaged the motors and other electrical appliances.Similarly it applies to the high voltage circuits too.

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