Zener gate and isolation gate
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I would like to ask: under what circumstances should a Zener-type safety barrier be used, and under what circumstances should an isolated safety barrier be used? There is a new rule now: Zener gates cannot be used in interlock circuits. But I don’t know why, so I hope an expert can provide an explanation. I look forward to your reply; I would be extremely grateful, thank you! ! !
Why isn’t anyone helping me answer this question? Is it possible that I’m in the wrong posting area?
Safety barriers mainly include Zener safety barriers and isolation safety barriers. Isolation barriers are used primarily for signal isolation and to counteract interference; however, they do not possess explosion-proof capabilities. Zener barriers, on the other hand, are used for explosion protection and to limit energy levels in order to ensure safety at the site
Zener safety barriers are relatively old products, and their production is now very limited. In circuits, fast fuses, current-limiting resistors, or voltage-limiting diodes are used to restrict the amount of electrical energy entering the system, thereby ensuring that only the necessary amount of energy is delivered to hazardous areas. Isolation safety barriers are mature products that are widely used today; they employ a circuit structure that provides electrical isolation between the input, output, and power supply, while also meeting the energy limitation requirements of intrinsically safe systems. Compared to Zener-based safety solutions, although it is more expensive, its outstanding performance advantages bring greater benefits to users’ applications.
Both the Zener barrier and the isolation barrier are essential components in intrinsically safe circuits. What I don’t understand is what the difference is between the field primary instruments used with the Zener barrier and those used with the isolation barrier If the energy required for the operation of the field instrument is high, then can’t the Zener diode be used? Which instruments on-site cannot use a Zener diode gate? Which instruments cannot use an isolation barrier? Which sea friend can give an example? Thank you! ! !
This post was last edited by liuronghai on 2016-12-2 09:16. For example, high-power three-wire instruments such as combustible and toxic gas detectors (with audible and visual alarms) cannot use safety barriers; modern isolation barriers have intrinsic current-limiting functions and do not require grounding, though they are more expensive! Zener diodes are inexpensive, but they require a ground resistance of less than 1 ohm; the requirements are quite stringent, so their use is not recommended.
Is the isolation barrier what we commonly refer to as an isolated safety barrier? Is there any difference between them?
To be precise, it should refer to isolators and isolation safety barriers; the former provides isolation for input, output, and power supply, while the latter not only possesses the isolation technology of the former but also comes with corresponding explosion-proof certifications. For details, please refer to the selection manuals for relevant products.
The Zener gate is an early-type product; initially, they were active Zener gates, and most of those still in use today are passive Zener gates. They are suitable for powering intelligent transmitter circuits in DCS systems, and compared to safety gates, they result in less power loss. However, they have many disadvantages when in use. Currently, with the development of electronic components, the power consumption of isolated safety barriers is becoming increasingly low; it is estimated that Zener barriers will be phased out in the future.