Varistor

A varistor is a voltage-dependent resistor that changes its resistance based on the applied voltage across it. At normal operating voltages, it has high resistance and minimal current flow, but when voltage exceeds a specific threshold, its resistance drops dramatically, allowing current to flow freely. This characteristic makes varistors ideal for surge protection circuits, where they divert dangerous voltage spikes away from sensitive electronic components. They are commonly found in power strips, circuit boards, and electrical equipment as protection devices against lightning strikes and power surges.