Different types of Intrinsically Safe (IS) barriers reside in electrical equipment such as gas detectors, fire detectors, alarms, and more mount in a hazardous area. IS barriers protect equipment from surges in the current that would otherwise risk turning the equipment into an ignition source.
Barriers limit the amount of energy allowed to pass into the hazardous area, inhibiting ignition in the atmosphere.
The ATEX Directive 2014/34/EU creates rules about equipment and protective systems intended for hazardous areas. As a brief history, the ATEX directive replaced the directive 94/9/EC in 2016 with only minor changes. Currently, Intrinsically Safe devices are the only product types the ATEX standards admit into 0 Zones. Zone 0 is a worksite or facility with a greater risk of hazard.
There are 2 types of Intrinsically Safe Barriers:
Isolated Barriers (Galvanic Isolators)
In addition to their explosion protection function, isolated barriers offer galvanic isolation to protect measurement and control circuits from signal distortion and dangerous surges. Also, these interface modules convert, standardize, and split measurement and control signals.
Zener Barriers (Shunt-diode safety barriers)
The Zener barrier prevents excessively high energy levels from transmitting between the non-explosion area to the hazardous area. Furthermore, interface modules are the right choice when galvanic isolation is not needed or otherwise provided.
At any rate, Intrinsically Safe Barriers should be located between the devices in the hazardous area and the control equipment (installed in a safe area).
HOW DO INTRINSICALLY SAFE BARRIERS WORK?
Intrinsic safety principles limit energy levels within circuits to avoid igniting the potentially explosive mixture, even in system failure. To summarize, there are two types of Intrinsically Safe Barrier controlling energy levels in an electrical circuit. Specifically, Zener barriers divert excess energy to the earth through fuse and Zener diodes. And Galvanic isolators isolate circuits in hazardous areas and those in safe areas through relays, transformers, and optoisolators.