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What are the functions of varistors

2021-09-03 16:10:29

With the improvement of power level, our production and life cannot be separated from the amount of electricity, and electricity has brought us unprecedented convenience. However, technology itself is a double-edged sword. To prevent damage from excessive voltage output, there is a resistor. There are many types of resistors. Let's first understand the function of a varistor.

1. The biggest function of the varistor is that when the voltage added to it is lower than its threshold value UN, the current flowing through it is extremely small, which is equivalent to a closed valve. When the voltage exceeds UN, its resistance value becomes smaller , so that the current flowing through it increases sharply, and the influence on other circuits does not change much, thereby reducing the influence of overvoltage on subsequent sensitive circuits. Utilizing this function, it is possible to suppress the abnormal overvoltage that is common in the circuit, and protect the circuit from being damaged by the overvoltage.

2. Varistors are mainly used for transient overvoltage protection in circuits, but because of their volt-ampere characteristics similar to semiconductor Zener tubes, they also have a variety of circuit component functions. For example, the varistor is a DC high-voltage small current voltage stabilizing element, and the stable voltage can reach more than thousands of volts, which cannot be achieved by the silicon voltage regulator; the varistor can be used as a voltage fluctuation detection element; it can be used as a DC level shift element; Used as a fluorescent starting element; can be used as a pressure equalizing element, etc.

3. Advantages of varistors and other surge suppressors:
(1) Better thermal characteristics are different from silicon diodes that only have one P-N junction to withstand surge currents. Zinc oxide varistors are composed of millions of P-N structures, which have better energy absorption and surge withstand capability.
(2) A varistor with a fast response speed has operating characteristics similar to other semiconductor elements. The conduction of the rheostat is very fast, and the delay is only in the range of nanoseconds, which can meet any practical needs.

(3) Stable voltage under over-temperature conditions. When the breakdown voltage is exceeded, once the ambient temperature exceeds the normal operating temperature range, the limit voltage of the Zener diode will increase with the increase of the ambient temperature, and when the limit voltage of the varistor exceeds the operating temperature range, it will remain almost unchanged . When the leakage current of the varistor increases with the temperature of the component body, the limiting voltage of the varistor does not change with the temperature.

The above is the introduction of the function of the varistor, I hope it will be helpful to everyone. Guangdong Zhimin Electronics Co., Ltd. is a non-governmental technology enterprise dedicated to the development and production of protective electronic components. Varistors are one of the company's main products, including high-energy varistors, ordinary varistors, circular varistors Resistors, etc., with various designs and stable performance.

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