The role of varistor

It is well known that the normal operation of a circuit board is composed of no capacitors and resistors. According to the test data, varistors are suitable protective devices for protecting sensitive electronic components. Let's get to know< Br/>Varistors are widely used in electronic circuits to protect the circuit from possible damage caused by sudden changes in the instantaneous voltage of the power supply system. The varistor is generally used in parallel in the circuit. When the voltage at both ends of the resistor changes sharply, the resistance short circuit will blow the current fuse and play a protective role. Varistors are often used for overvoltage protection and voltage stabilization of power supply in circuits. When the high voltage comes, the resistance of the varistor will be reduced and the current will be shunted to prevent damage or interference by excessive transient voltage. Therefore, sensitive electronic components are protected

Metal oxide MOV varistor is made of zinc oxide (zinc oxide) Non-linear resistance element with main component. The surge current tolerance and nonlinear coefficient of MOV are very large, and the resistance is very high below the threshold voltage. There is almost no current flowing, and the resistance drops sharply when the threshold voltage is exceeded, and the amplified current can discharge; Because of this characteristic, it plays a great role in absorbing abnormal voltage and lightning surge as a protective element of electronic and electrical equipment. Extended data When the voltage applied to the rheostat is lower than its threshold value, the current flowing through it is very small, equivalent to a resistance with infinite resistance. In other words, when the voltage applied to it is lower than its threshold value, it is equivalent to a switch in the off state. When the voltage applied to the rheostat exceeds its threshold, the current flowing through it increases sharply, which is equivalent to a small resistance. In other words, when the voltage applied to it is higher than its threshold value, it is equivalent to a closed switch< Br/>Many people also have the mistake of thinking that the varistor can protect sensitive electronic components. They think that the varistor plays a very important role. In the actual circuit protection scheme, the varistor can not provide complete voltage protection. It is necessary to have a variety of protective devices to form a protective circuit< Br/>Because the energy or power that the varistor can bear is limited, it cannot provide continuous overvoltage protection. The continuous overvoltage will damage the protective device (varistor), cause damage to the equipment, and may cause fire hazard