Zenamic Metal Oxide Varistors

ATC Semitec offer a wide range of metal oxide varistors from our leading manufacturer Semitec.

Metal oxide varistors are used to control high transient voltage surges in electronics and electrical circuits to safe levels. When a voltage surge exceeds the specified voltage, the varistor supresses the voltage to protect the circuit.

What is a Varistor?

In general, a varistor (variable resistor) is an electronic component with an electrical resistance that varies with the applied voltage. Also known as a voltage-dependent resistor, it has a nonlinear, non-ohmic current–voltage characteristic that is similar to that of a diode. But, unlike a diode, it has the same characteristic for both directions of traversing current.

At low voltage it has a high electrical resistance which decreases as the voltage is raised.


The advantages if using a varistor over other transient suppressors include:

  • Improved peak handling capability
  • High speed of response
  • High level of reliability – operating even at high temperatures
  • Offers cost- effective and compact solution

Typical Applications include:

  • Semiconductor device protection: Diodes, transistors, thyristors, IC etc.
  • Home electronics protection: TVs, air conditioners, refrigerators, microwave ovens, etc.
  • Office automation equipment protection: PPC copiers, fax machines, PCs, etc.
  • Industrial equipment protection: Robots, water heaters, machining equipment, etc.
  • Inrush surge protection: Electromagnetic clutches/brakes, relay control devices, circuit breakers etc.
  • Automotive electronics circuits
  • Vending machines, communication/broadcasting equipment, etc.

For further technical information, see our Frequently Asked Questions section

Call us today on 01606 871680 or complete the Contact us form, to discuss your application’s thermal sensor requirements.  Using our extensive technical knowledge and innovative supplier base, we will work with you to provide the optimum solution for your product.

  • Products
  • FAQs
  • Semitec Zenamic MOVs

    Zenamic MOVs have large surge current handling capabilities.

    • Peak current surges of up to 6500A (8/20 s) and peak power surges of up to 565J (10/1000 s) respectively can be limited by these fast-acting devices.