The difference between varistor and voltage equalizing resistor

1. The important function of the voltage equalizing resistor is to hold the voltage dividing principle so that the voltages under the respective capacitors are equal. If there is no such, the voltage of each capacitor terminal will be different due to the difference of the capacity and insulation resistance of each capacitor. For example, there are 10 capacitors with a withstand voltage of 100V. When there is no voltage equalizing resistor connected to the two ends of the 1000V voltage, some of the lower voltages can be broken down and penetrated. After the breakdown, the other capacitors are quickly broken down.

2. The varistor means that the resistance value varies with voltage in the range of positive current and voltage, so the resistor value is sensitive to voltage.

The varistor is a voltage limiting type protection device. Holding the nonlinearity of the varistor, when the overvoltage is between the two poles of the varistor, the varistor can clamp the voltage to a smooth voltage value, thus completing the protection of the latter circuit. The important parameters of the varistor are: varistor voltage, current capacity, junction capacitance, response time, and so on.

The characteristic of the varistor is that when the voltage applied below it is lower than its threshold 'UN', the current flowing through it is extremely small, and as for a valve that is closed, when the voltage exceeds UN, its resistance is It becomes smaller, so that the current flowing through it surges and the influence on other circuits does not change much, thereby reducing the influence of the overvoltage on the subsequent sensitive circuit. Holding this function can suppress the abnormal overvoltage that appears repeatedly in the circuit and protect the circuit from overvoltage.

The varistor is used throughout the electronics to protect against circuit damage due to sudden changes in the voltage of the power supply system. When the high voltage is separated, the resistance of the varistor is low and the current is shunted, and the threat is destroyed or disturbed by an excessive transient voltage. This protects sensitive electronic components.