An IS system usually consists of safe area equipment, a safe to hazardous area interface, cables and junction boxes, and field (hazardous area) equipment. The system is designed to guard against the possibility of particular faults occurring.
The intrinsic safety concept applies to the whole system and not to any one item only.
Associated apparatus (interface) #
The equipment in the safe area is connected to equipment in the hazardous area via the interface, which is the associated apparatus.
The function of the interface is to limit the energy into the hazardous area and is often called as the I.S. Safety Barrier.
There are two types of I.S barriers:
- Zener barrier
- Galvanic isolation barrier
The interface may be incorporated inside the safe area apparatus (e.g. a recorder with an energy-limited input from a sensor I the hazardous area).
