Varistor nominal parameters

The varistor is represented by the letter “MY”. If J is used for household use, the following letters W, G, P, L, H, Z, B, C, N, and K are used for voltage regulation, overvoltage protection, and high frequency. Circuit, lightning protection, arc extinguishing, noise cancellation, compensation, degaussing, high energy or high reliability. Although varistor can absorb a large amount of surge energy, it cannot withstand continuous currents above the milliamp level, and must be taken into account when used as overvoltage protection. For the selection of varistor, two parameters of nominal varistor voltage V1mA and flow capacity are generally selected.

The so-called varistor voltage, that is, the breakdown voltage or the threshold voltage. Refers to the voltage value at the specified current. In most cases, the voltage value measured when a 1 mA DC current is applied to the varistor, the varistor voltage range of the product can range from 10-9000V. Can be selected according to specific needs. Generally, V1mA=1.5Vp=2.2VAC, where Vp is the peak value of the rated voltage of the circuit. VAC is the rms value of the rated AC voltage. The choice of the voltage value of the ZnO varistor is crucial, and it is related to the protection effect and service life. If the rated power supply voltage of a household appliance is 220V, the varistor voltage value V1mA=1.5Vp=1.5×1.414×220V=476V, V1mA=2.2VAC=2.2×220V=484V, so the breakdown voltage of the varistor can be Choose between 470-480V.

The current capacity, that is, the peak value of the pulse current is a pulse current value when the varistor voltage does not change by more than ± 10% for a predetermined surge current waveform and a predetermined number of surge currents when the ambient temperature is 25 °C.