Varistors are nonlinear resistive semiconductor components with symmetrical volt-ampere characteristics whose resistance changes in functional dependence of the voltage that flows through them. When the value of the voltage reaches the threshold value of the varistor, regardless of the direction, its resistance is extremely high and in practice there is no current flow. Etymologically, the name of the varistor is formed by the English words “variable resistor”. Often they are labeled with the abbreviation VDR (voltage dependent resistor).
One of the most important characteristics of varistors is their threshold voltage (operating voltage), other parameters are: operating (rated) current, maximum power dissipation, etc.
Varistors are connected in parallel to the power of electronic networks and are used to protect other components or devices in the circuit from pulsed voltage that may be caused by thunder, switching or malfunction of the supply network.
Vikiwat Ltd. offers a wide range of varistors and other semiconductor items at competitive prices.