Category | Varistors

Introduction to Varistors

Posted on 10 April 2020

              Varistors are voltage-dependent resistors. They consist of a semiconductor material which is pressed in pulverised form and then sintered to create a solid disc. Their effect is based on the existence of numerous random pn-junctions at the contact points between the little fragments or grains. Most varistors are [...]

Selection Guide - Varistors

Posted on 07 April 2020

    Choosing a varistor involves three main steps: Select varistors that are suitable for the operating voltage. Determine the varistor that is most suitable for the intended application in terms of: a) surge current b) energy absorption c) average power dissipation (for a and b also estimating the number of repetitions) Determine the maximum [...]

Overvoltage Protection with Varistors

Posted on 26 March 2020

    Overvoltages are generally categorized according to where they originate. Internal overvoltages Internal overvoltages originate in the actual system which is to be protected, e.g. through inductive load switching arcing direct coupling with higher voltage potential mutual inductive or capacitive interference between circuits electrostatic discharge (ESD) External overvoltages External overvoltages affect the system that [...]