Varistors

Varistors are devices that provide excellent transient voltage suppression and are a type of non-linear device that feature similar characteristics to Zener diodes. They are used to protect vulnerable electronic circuits and components from overvoltage conditions that can cause damage. Any potentially destructive overvoltage energy is dissipated as heat.

Types of Varistor

Metal oxide varistors

Metal Oxide Varistors (MOVs) are typically constructed from zinc oxide and combined with small additions of other metal oxides such as cobalt, manganese or bismuth. These materials are sintered into ceramic casings during manufacture. Although MOVs are available in different formats, they are most commonly radial leaded discs.

Applications:

Suppression of lightning and other high levels of transient energy
Low voltage power supplies in DC circuits
Low voltage power supply in automotive applications
Protection from internal transients within capacitor discharges, relay switching and inductive load switching

Ceramic transient voltage

Ceramic transient voltage suppressors are a type of variable resistor that are designed to respond to momentary conditions of overvoltage. They are more effective than other types of overvoltage protection components, such as varistors or gas discharge tubes, as they respond faster to the changing conditions. This particular type of transient voltage suppressor is made from ceramic.

Applications:

Ceramic transient voltage suppressors are used as part of electronic circuits to protect data or transmission lines. They work to protect against both unidirectional and bidirectional electrostatic discharge. This kind of sudden voltage spike can be caused either internally or externally, for example in the form of lightning or motor arcing.