Varistor is a special resistance device with nonlinear volt-ampere characteristics, which is mainly used for circuit overvoltage protection. This resistance device is used in parallel in the circuit, when the voltage in the circuit exceeds the set breakdown voltage, the varistor will quickly absorb the excess current, thereby protecting the sensitive device in the circuit from damage.
The working principle of varistor is based on its internal structure, which can support the rapid outflow of current under certain conditions. When the voltage in the circuit exceeds the preset value, the varistor will quickly turn on and absorb the excess current, thereby protecting the circuit. In addition, the response time of the varistor is very fast, in the order of nanoseconds, which allows it to respond quickly to overvoltage situations in the circuit.
In terms of selection, it is necessary to consider the breakdown voltage, internal resistance and external resistance of the varistor. These parameters determine whether the varistor can effectively protect a particular circuit. For example, choosing the right breakdown voltage can ensure that the varistor provides protection without affecting normal operation.
Although varistors are very useful in many application scenarios, they also have some limitations. Because of its large junction capacitance, it is not suitable for direct application in the protection of high frequency signal lines. In the protection applications of AC circuits, leakage problems may be increased due to the presence of junction capacitors.
Varistor is an important electronic protection element, which provides overvoltage protection for circuits through its unique nonlinear voltammetry characteristics. The right selection and application can maximize its protective effect while avoiding potential negative effects.
