weidy Industrial, with 18 years of experience in the research, development, customization, production, and sales of varistors, offers a wide range of products. We support free samples and on-demand customization, and provide a 5-year quality assurance service. Today, the brand editor of varistors will introduce the working principle of varistors.

Varistors are a type of variable resistors that work based on the piezoelectric effect and the electrostrictive effect. The piezoelectric effect refers to the phenomenon where certain materials generate charge distribution on their surfaces when subjected to pressure or strain. These materials are known as piezoelectric materials. The electrostrictive effect refers to the interaction between the electrical and mechanical properties of a material, specifically the mutual influence between the electric field and the strain field.

The main materials used in varistors are zinc oxide (ZnO) or zinc selenide (ZnSe), which exhibit both the piezoelectric effect and the electrostrictive effect. Under normal conditions, the resistance of these materials is high, ranging from hundreds of megaohms to even gigaohms. However, when subjected to external forces, strain occurs, resulting in a change in their resistance value.
When a varistor is subjected to external force, it undergoes strain, leading to charge distribution and the formation of an electric field. This electric field causes the movement of free electrons and holes in the zinc oxide or zinc selenide, thereby changing the resistance value. The resistance value of a varistor varies with the magnitude of the external force and can be used to detect or limit current or voltage.
In summary, varistors utilize the piezoelectric effect and the electrostrictive effect to change their resistance values, thereby enabling the detection and limitation of current or voltage.