SSC JE Electrical Engineering 2017 Set 4 Paper

Metal oxide varistor protect against high voltage varistor is non linear resistance. Resistance of varistor is dependent on voltage applied. if high voltage is applied the resistance of varistor reduce and protect the system through heavy current flow through ground.
$\left[\mathit{I}=\mathit{K}{\mathit{V}}^{\mathit{n}}\right]$
n = 2 to 6 for silicon carbide
n = 20 to 50 for zinc oxide.