The working principle and function of varistor

1. The working principle of varistor

When the varistor is in operation, each varistor unit is subjected to surge energy, and the varistor units are substantially evenly distributed throughout the resistor body, that is, the entire resistor body bears energy, unlike The nano-polar regulator tube is just the junction area to bear the electric power, which is why the ceramic varistor has a much larger flow and energy rating than the Zener diode. Its resistance value varies with the terminal voltage. The main characteristics of the varistor are wide operating voltage range (6-3000 volts, divided into several gears), fast response to overvoltage pulses (several to tens of nanoseconds), and high resistance to inrush current (up to 100 amps - 20 kA), low leakage current (less than a few to several tens of microamperes), small temperature coefficient of resistance, high quality and low price, small size, is an ideal protection component.

2. The role of varistor

The biggest characteristic of a varistor is that when the voltage applied to it is lower than its threshold "UN", the current flowing through it is extremely small, equivalent to a shut-off valve. When the voltage exceeds UN, it flows. Its current surges, which is equivalent to the valve opening. With this function, it is possible to suppress abnormal overvoltages that often occur in circuits and protect circuits from overvoltages.

A varistor is a component with transient voltage suppression that can be used in place of a combination of a transient suppression diode, a Zener diode, and a capacitor. Varistors protect circuits in ICs and other devices from electrostatic discharges, surges, and other transients such as lightning strikes. When using, it is only necessary to connect the varistor to the protected IC or device circuit. When the voltage is higher than a certain value, the resistance of the varistor decreases rapidly, and a large current is turned on, thereby protecting the IC or the electric appliance. Equipment; when the voltage is lower than the working voltage of the varistor, the varistor has a very high resistance value and is almost open, so it does not affect the normal operation of the device or electrical equipment.