SPD varistor some common sense

SPD varistorThe manufacturer believes that the varistor has strong electrical characteristics and is a very mature electronic component, which can be used in various electronic equipment to protect the claw, reduce lightning damage, improve the stability and use characteristics of the equipment, and can be used in lightning protection and automotive electrical and ignition systems. The resistance material of rheostat is semiconductor, so it is a kind of semiconductor resistance. Currently,‘ is widely used; Zinc oxide’ (ZnO) varistor, its main material is composed of divalent element (Zn) and hexavalent element oxygen (O). So in terms of material, zinc oxide varistor is a kind of“ II-VI oxide semiconductor&rdquo

The SPD varistor manufacturer believes that the main characteristic of the varistor is that when the voltage applied to it is lower than its threshold value‘ UN’ The current flowing through it is very small, equivalent to a closed valve. When the voltage exceeds UN, the current flowing through it will surge, equivalent to the valve opening. Through this function, the abnormal overvoltage that often occurs in the circuit can be suppressed and the circuit can be protected from overvoltage damage

The manufacturer of SPD varistor believes that the varistor is a component with transient voltage suppression function, which can be used to replace the combination of transient suppression diode, zener diode and capacitor. The rheostat can protect the integrated circuit and other devices from the damage of electrostatic discharge, surge and other transient current (such as lightning, etc.) When in use, only connect the rheostat in parallel to the IC or equipment circuit to be protected. When the voltage is instantaneously higher than a certain value, the resistance value of the rheostat will drop rapidly and transmit large current to protect the IC or electrical equipment. When the voltage is lower than the working voltage of the varistor, the resistance of the varistor is extremely high, almost open circuit, so it will not affect the normal operation of the device or electrical equipment

SPD varistorThe manufacturer thinks that the voltage is the breakdown voltage or threshold voltage. It refers to the voltage value under the specified current. In most cases, it is the voltage value measured when 1mA DC current enters the varistor. The voltage range of its products can be 10-9000V. It can be selected correctly according to specific needs. VAC is the effective value of rated AC voltage. The selection of voltage value of ZnO varistor is very important, which relates to the protection effect and service life

The manufacturer of SPD varistor believes that the current carrying capacity, i.e. the peak value of zui large pulse current, is the value of zui large pulse current when the ambient temperature is 25. For the specified pulse current waveform and times, the variation of the varistor voltage shall not exceed 10%. In order to prolong the service life of the device, the amplitude of the surge current absorbed by ZnO varistor should be less than the Zui flux given in the product manual. However, from the perspective of protection effect, it is required to select a larger flux

These are some knowledge points about varistors. I hope you can study and understand relevant knowledge carefully