Series and pairing of varistors

Varistors can easily be used in series. After two varistors with the same diameter (the same flow rate) are connected in series, the lacquer pressure-sensitive voltage, continuous working voltage and limiting voltage are added together, and the flow rate index is unchanged. For example, in the high-voltage power arrester, the continuous working voltage is required to be up to thousands of volts, tens of thousands of volts, which is obtained by overlapping multiple ZnO varistor valve pieces (series).

The varistors can be connected in parallel to obtain a large flow rate, or to reduce the current density in the resistance body to reduce the limiting voltage under the condition that the peak surge current is fixed.

When a large flow rate is required [for example, 8/20, (50-200) KA] and the pressure-sensitive voltage is relatively low (for example, less than 200V), the diameter/thickness ratio of the resistance body is too large, which makes it difficult in manufacturing technology. Moreover, with the increase of the diameter of the resistance body, the microuniformity of the resistance body becomes worse. Therefore, the flow rate cannot increase proportionally with the area of the resistor. It may be reasonable to use smaller diameter resistors in parallel.

Due to the high nonlinearity, the parallel connection of the varistor plates requires special care. Only after careful matching, the same parameters of the resistor plates in parallel, can ensure that the current is evenly distributed among the resistance plates. For this demand, the company specializes in providing users with matching resistors.

In addition, when several varistors are connected longitudiently, using paired varistors with the same parameters, the voltage difference that appears in the transverse direction can be small when the impact incurs. In this case, pairing also makes sense.