"Metrosil" non-linear resistors are manufactured from a semi-conducting material with the distinctive property that its electrical resistance depends on the applied voltage. This enables them to act as an "electric safety valve" to protect equipment and insulation from the effects of over voltages. Millions of Metrosil varistors have been sold throughout the world with current ratings varying from microamps to kiloamps and capable of absorbing energies from 10 to 50,000 joules per disc. The wide range of energy absorption ratings and options in assembly type mean that they are suitable for many different applications, including exciter discharge, relay protection and current transformer protection and other applications as detailed in our Application Selector. Metrosil is part of the M&I Materials Group, operating from an integrated site located in Manchester (UK), the main facility where Metrosil is manufactured occupies a 5,000 m2 production unit.