Varistor lightning protection features

Varistors are often used in the lightning protection of instrument equipment power supply. Anti-surge design In these applications, varistor is usually used together with gas discharge tubes, fuses, thermistors and other devices to better play together. effect. The varistor lightning protection has the following ten characteristics:

1. Since the varistor arrester does not require a series gap, the structure is simple, the volume is small, the weight is light, and the service life is long;

2. Stable performance. Since the varistor arrester has no gap, there is no problem that the gap discharge voltage is affected by external factors, and there is no problem of gap discharge dispersion and misoperation;

3. Easy to manufacture, suitable for automated mass production;

4. It is convenient to make DC arrester. Because it has no gap, no arc, and good nonlinear resistance characteristics, the difficulty in manufacturing DC arresters can be solved;

5. Good protection performance. The protection performance of the varistor arrester is independent of the discharge voltage of the gap, and is determined only by the residual voltage of the valve. The residual pressure of the zinc oxide valve plate is lower, so the protection performance is good;

6. Can withstand multiple lightning strikes. After the lightning current passes through the metal oxide arrester, there is no continuous flow of the power frequency, so the energy passing through the arrester is greatly reduced, so it can withstand multiple lightning strikes;

7. Large flow capacity. The metal oxide arrester has a higher flow capacity than the silicon carbide arrester. When the flow capacity of the single piece of zinc oxide valve is not satisfied, in addition to increasing the diameter of the valve plate, multiple arresters can be used in parallel to improve the flow capacity. ;

8. The varistor has poor nonlinear characteristics (large dynamic resistance);

9. The limiting voltage (clamping voltage) is high at high currents;

10. When the voltage is low, the leakage current is large and it is easy to age.