What is Zener barrier

Fast fuse, current limiting resistor or voltage limiting diode are used in Zener safety barrier circuit to limit the input electrical energy, so as to ensure the energy output to the hazardous area. Its principle is simple, the circuit is easy to realize, and the price is low. However, due to the defects of its own principle, its reliability in application is greatly affected, and its application scope is limited. The reasons are as follows:
1. The installation position must have a very reliable grounding system, and the grounding resistance of the zener safety barrier must be less than 1 Ω, otherwise the explosion-proof safety protection performance will be lost. Obviously, such requirements are very harsh and difficult to guarantee in practical engineering applications.
2. It is required that field instruments from hazardous areas must be isolated, otherwise the signal cannot be transmitted correctly after being connected to the earth through the grounding terminal of Zener safety barrier, and the signal anti-interference ability will be directly reduced due to signal grounding, which will affect the stability of the system.
3. Zener safety barrier has great influence on power supply, and it is also easy to damage Zener safety barrier due to power supply fluctuation.
4. Because the circuit principle of Zener safety barrier needs to absorb the energy of the input circuit, it is easy to cause output instability.