Understand the Voltage and Leakage Current of Varistors

Jul. 26, 2021

Varistor is a resistance device with nonlinear volt-ampere characteristics. It is mainly used for voltage clamping when the circuit is subjected to overvoltage and absorbs excess current to protect sensitive devices. In daily use, we must understand clearly the voltage and leakage current of the varistor.

1) Varistor Voltage UN (U1mA): Varistor voltage is the voltage across a varistor when a 1mA DC current is passed through the component. Varistor voltage is also commonly represented by the symbol U1mA. The tolerance voltage of the varistor voltage is generally ±10%. In the test and actual use, a 10% drop in the varistor voltage from the normal value is usually used as the criterion for the failure of the varistor.

2) Continuous working voltage UC: refers to the AC voltage (effective value) Uac or DC voltage Udc that the varistor can withstand for a long time. Generally Uac≈0.64U1mA, Udc≈0.83U1mA

3) Clamping voltage (limiting voltage) VC: The clamping voltage value refers to the voltage appearing on the varistor when the specified 8/20μs wave impulse current IX (A) is applied to the varistor.

4) Leakage current Il: the current that flows when a DC voltage Udc is applied to the varistor. When measuring the leakage current, usually add Udc=0.83U1mA voltage to the varistor (sometimes 0.75U1mA is also used). Generally, the static leakage current Il ≤ 20μA is required (there are also requirements ≤ 10μA). In actual use, what is more concerned about is not the value of the static leakage current itself, but its stability, that is, the rate of change after the impact test or under high temperature conditions. After the impact test or under high temperature conditions, the rate of change does not exceed one time, which is considered stable.

Understand the Voltage and Leakage Current of Varistors

The above is the relevant content of this article. Hopefully it can help everyone to have a better understanding of varistor. Dongguan Zhixu Electronic Co., Ltd. (also JYH HSU(JEC))  has a full range of varistor models. JEC has passed ISO9001:2015 quality management system certification; JEC safety capacitors (X capacitors and Y capacitors) and varistors have passed national certifications of the main industrial powers across the world; JEC ceramic capacitors, film capacitors and super capacitors are in compliance with environmental protection indicators. Welcome to contact us for free samples or any questions. 

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