Additional Information

Varistors are nonlinear voltage-clamping devices primarily composed of zinc oxide, typically applied in parallel across the protected circuit. When the voltage is below the varistor voltage, they exhibit high resistance; once the threshold is exceeded, the resistance sharply decreases, allowing surge current to be diverted and clamping the voltage within a safe range. MOVs offer the advantage of high surge current capability, but they are subject to certain aging effects (increased leakage current after repeated surge events). Selection considerations include the varistor voltage, maximum continuous operating voltage, peak surge current, and energy absorption capability. They are widely used for transient overvoltage protection at power supply inputs.