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Specialist Materials for Industry and Science

Welcome to Metrosil Silicon Carbide Varistors

Metrosil non-linear resistors are high performance surge protection devices that provide excellent service in a wide range of applications around the globe.

At M&I Materials we have been developing and producing Metrosil for over 60 years and pride ourselves on delivering manufacturing excellence and high standards of technical support.

Manufactured from a semi-conducting material with the distinctive property that its electrical resistance depends on the applied voltage enabling it to act as an 'electrical 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.

Why Metrosil is the Right Surge Protection for You

  • Superior Energy Absorption
  • No De-rating
  • Low Maintenance

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 has an enviable track record in systems ranging from Hydro power generators to rail networks and it is the prime choice for demanding applications and critical situations.


  • Apiezon
  • Metrosil
  • Midel
  • Wolfmet

Products of M&I Materials Ltd.