Reasons and Solutions for Burnout of Varistors

Varistors are generally made of semiconductor materials such as zinc oxide, and their working principle is to use the movement of impurity ions in semiconductor devices under the action of an electric field to achieve changes in resistance values. When the voltage increases, impurity ions will be accelerated by the electric field, resulting in a decrease in resistance value; On the contrary, when the voltage decreases, the movement of impurity ions is alleviated, and the resistance value increases. During the use of varistors, burning may sometimes occur. This article will provide a detailed introduction to the reasons and solutions for the burning of varistors.

1、 Reasons for combustion of varistors

1. Overvoltage: Overvoltage is one of the main reasons for the combustion of varistors. When overvoltage is applied to a varistor, the resistance value will sharply decrease, leading to a sharp increase in circuit current and combustion of the varistor.

2. Overcurrent: Overcurrent is one of the reasons for the combustion of varistors. When excessive current passes through the varistor, its internal semiconductor devices will overheat, causing the varistor to burn.

3. Excessive temperature: Excessive temperature can also cause combustion of the varistor. When the varistor is exposed to high temperatures for a long time, its internal semiconductor devices will be damaged, leading to changes in its resistance value and even combustion.

4. Humidity: Excessive humidity can also cause combustion of varistors. When the varistor is exposed to high humidity for a long time, its internal semiconductor equipment will be corroded, causing changes in its resistance value and even burning.

2、 A Solution to the Burnout Problem of Varistors

1. Choose a suitable varistor: When designing a circuit, choose a suitable varistor based on the voltage, current, power, and other parameters of the power supply. Choosing a suitable varistor can effectively avoid issues such as overvoltage and overcurrent, thereby reducing the risk of varistor combustion.

2. Control circuit parameters: When using a varistor, it is necessary to control the voltage, current, and other parameters of the circuit to prevent excessive current or voltage from damaging the varistor. Varistors can be maintained by adding protective circuits.

3. Control environmental standards: When using varistors, factors such as environmental temperature and humidity must be controlled to prevent damage to the varistors due to excessive temperature or humidity. Varistors can be maintained by installing heat sinks and moisture-proof equipment.

4. Application of more durable varistors: Some varistors have more durable characteristics and can be applied in more harsh environments, such as high temperature and humidity. This type of varistor can be used to improve the stability of the power supply.

5. Check the circuit: Check the varistor in the circuit on time to avoid invalidation or burning of the varistor due to long-term use, environmental changes, or other reasons. A multimeter and other equipment can be used to test the varistor in a circuit.

When using varistors, it is necessary to select appropriate varistors, control circuit parameters, control environmental standards, apply more durable varistors, and check the circuit in a timely manner to prevent the combustion of varistors. Through reasonable application of protection, the stability and service life of the varistor can be improved, ensuring the normal operation of the power supply.