Mohit,

I'm not quite sure, whether I understood you correctly. But a Varistor is not a fuse! It does not break like a fuse. It's limiting the voltage to a certain level, as I stated in my last reply. A varistor is high ohmic below threshold voltage and becomes low ohmic above threshold level.
I would highly recommend you to make some search in google. Type 'varistor' or 'mov'. Look for datasheets. Nearly all manufacturers (e.g. EPCOS) do have some good tutorials, which explain, how this thingy works and how it has to be designed.

Kai