Summary varistor characteristics

Varistors are voltage limited protection devices. Using the non-linear characteristics of the varistor, when overvoltage occurs between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed voltage value, thereby achieving the protection of the subsequent circuit.

When the voltage across the varistor is below its threshold, the current flowing through it is minimal, and it is equivalent to a resistor of infinite resistance. That is, when the voltage applied to it is lower than its threshold, it is equivalent to an off-state switch. When the voltage across the varistor exceeds its threshold, the current flowing through it surges, which corresponds to a resistor with infinite resistance. That is, when the voltage applied to it is higher than its threshold, it is equivalent to a closed state switch.

Varistors are characterized as follows:

1. In parallel with the pressure limiting protection device in the line;

2. No polarity;

3. The reaction speed is fast, generally not exceeding 25NS;

4. Strong surge withstand ability, up to 70KA;

5. Body size is varied, from 5D, 7D, 10D, 14D, 20D, 40D, etc., even larger size (d and disk handwritten letters, circular meaning; S, is the square's first letter, square meaning);

6.Wide voltage range, generally from 18V ~ 1800V;

7. Is mainly used for low frequency signal line protection, such as power products.