Effect advantage analysis of SPD varistor

SPD varistoris one of the most widely used voltage limiting devices, including silicon carbide varistor and zinc oxide varistor. The commonly used zinc oxide varistor is an overvoltage protection device. It is made of zinc oxide as raw material, a variety of trace metal oxides, mixed and sintered, and the outer surface is sealed with epoxy resin

What is the use of SPD varistor? The 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, its resistance becomes smaller, so that the current surge flowing through it has little impact on other circuits, thus reducing the impact of overvoltage on subsequent sensitive circuits. Through this function, the circuit can be protected from overvoltage damage and the abnormal overvoltage that often occurs in the circuit can be controlled. At the same time, the varistor also plays a very important role. Varistors are mainly used for transient overvoltage protection in circuits, but because their voltage-ampere characteristics are similar to semiconductor voltage regulators, they also have various functions as circuit components. For example, the varistor is a DC high-voltage small-current voltage stabilizing element, whose stable voltage can reach thousands of volts, which is beyond the reach of silicon voltage stabilizing tube. Rheostats can be used as fluorescent starting elements; As DC translation potential element; It can be used as a voltage fluctuation detection element; It can be used as voltage equalizing element, etc

SPD varistorfunction and advantages: When the voltage applied on the varistor 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, it is equivalent to a switch in the off state. When the voltage applied to the varistor exceeds its threshold, the current flowing through it will surge, which is equivalent to a resistance with infinite resistance. In other words, when the voltage applied to it is higher than its threshold, it is equivalent to a closed switch

SPD varistorAdvantages compared with other surge suppressors: 1. Better thermal characteristics. Unlike silicon diodes, which have only one pn junction to withstand surge current, zinc oxide varistors are composed of millions of pn junctions, which have better absorption capacity and surge capacity. 2. Fast response. The rheostat has similar working characteristics with other semiconductor components. Because the conduction of the rheostat occurs very fast and the delay is only within the nanosecond range, it can meet any practical requirements. 3. Stable voltage under over-temperature condition. When the breakdown voltage is exceeded, once the ambient temperature exceeds the normal operating temperature range, the limit voltage of Zener diode will increase with the increase of ambient temperature, while the limit voltage of the varistor will almost remain unchanged when it exceeds the operating temperature range. When the leakage current of the varistor increases with the temperature of the element, the limiting voltage of the varistor will not change with the temperature