The ZOV varistor has three functions in the simple summary of the circuit: first is overvoltage protection; second is lightning strike requirements; thirst is safety test requirements.
The ZOV varistor is not a sensory pressure. It is a voltage susceptor. It is a bit like a fuse. It will break down beyond its own voltage and be protected by an open circuit.
The ZOV varistor is often used as an overvoltage protection device, but its current capacity is large, but its energy capacity is not large. In addition, its impulse current maximum pulse width is much smaller than the actual pulse current width of large and medium power semiconductor systems. Short circuits or explosions often occur.
Why the ZOV varistor burnout ? Here I will tell you.
1. aging failure, the performance of the leakage current increases, the ZOV varistor voltage drops significantly until zero.
2. Transient overvoltage damage.
3. The number of overvoltage protections;
4. the surrounding working temperature;
5. Whether the ZOV varistor is squeezed;
6. Whether the ZOV to pass the quality certification;
7. The surge energy is too large and exceeds the absorbed power;
8. the pressure is not enough;
9. current and surge are too large and so on.
The safety of the use of ZOV varistors has always been a problem that needs attention. Because ZOV varistor is widely used in household appliances and other electronic products, it functions as overvoltage protection, lightning protection, suppression of inrush current, absorption of spikes, limiting, high voltage arc extinguishing, noise cancellation, and protection of semiconductor components. . It is recommended to use high quality ZOV varistor.