What is the function of a Zener gate?
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What is the function of a Zener gate? What is the difference between it and an intrinsically safe type? How should it be selected?
It is used in intrinsically safe systems. It is used in conjunction with the isolation barrier; that’s all there is to it.
The isolation barrier is advantageous, as it separates the field side from the cabinet side into two distinct sections (including power supply and signal processing); such a design enables energy to be better confined within a certain range. Moreover, the shielding of the instrument cable can be grounded separately on the field side and at the cabinet side. Zener gates, on the other hand, rely primarily on equipotential grounding; if there are issues with the grounding, it is possible that a large portion of the system could fail as a result. We encountered this problem at our previous sites; later on, we started using isolation fences. See the link: http://bbs.hcbbs.com/thread-204501-1-1.html
A Zener-type safety barrier generally consists of a current-limiting resistor that limits the output current at the intrinsically safe terminal, a voltage-limiting and stabilizing diode (Zener diode) that controls the output voltage at the intrinsically safe terminal, and protective components (fast fuses, current-limiting resistors) that prevent the stabilizing diode from being damaged. Depending on the protective element, they are further divided into resistor-protected safety gates and fuse-protected safety gates. Intrinsic safety refers to a condition of an instrument that involves the instrument itself being intrinsically safe, along with the cables and safety barriers, all working together as a single unit. In other words, the Zener safety barrier is a means used in one of the steps to achieve intrinsically safe conditions.
Can be used for low-cost explosion protection in process control systems
Zinasan is used to meet explosion-proof requirements; it does not provide power supply. There is also an explosion-proof isolation barrier that supplies 24VDC power