Factors to consider when using varistor

The varistor is generally used in parallel in the circuit. When the voltage across the resistor changes abruptly, the short circuit of the resistor blows the current fuse to protect it. Varistors are used in circuits and are often used for power supply overvoltage protection and regulation. The reliability of a power surge protector depends to a large extent on the correct use of the varistor.

In particular, in the lightning protection design of the power supply, the differences in power quality, the frequency of lightning strikes and strength, the installation and use of the protected equipment, and the impact tolerance are also considered. Photocopy the set. The designed lightning protection protective circuit shall be tested and verified under the conditions of use in the field or under the simulated conditions as close as possible to the real situation.

The varistor has a high impedance (mega ohms) relative to the protected electronic component during rest, and does not change the design circuit characteristics, but when an instantaneous surge voltage occurs (crossing the breakdown voltage of the varistor) At this time, the impedance of the varistor becomes low (only a few ohms) and causes a short circuit in the original line, in other words the electronic product or component is thus protected.

Main use: lightning protection, overvoltage protection. For example, if the power transformer is placed in the lightning arrester at the entrance end, lightning protection can be applied. The electronic device is placed in the varistor at the input end of the power grid. Once the grid voltage is raised, the varistor will not recover the breakdown short circuit and the fuse will also be disconnected. Prevent overvoltage from entering the board. There are many varistor applications in air conditioning line boards.