An IS barrier (also called an intrinsic safety barrier) is, quite simply, an electronic safety device that is used to protect a circuit or instrument located in a hazardous location from becoming an ignition source.
Since this IS barrier is vitally important to safety, it is critical that the energy allowed into the field is limited to values known to be non-ignition capable.
IS barriers are unique!
What is unique about an intrinsic safety barrier is the amount of redundancy and safety built into the device. The design of an IS barrier guarantees the circuit or instrument cannot be the source of ignition under a wide range of operational and fault conditions. Many special design features are included in a typical intrinsic safety barrier including:
- Over-sizing (wattage de-rating) components
- Addition of two and three levels of redundancy
- Inclusion of spacing between circuit board traces and component leads
- Overall amount of isolation required on transformers and relays
As a result, the design characteristics make an intrinsic safety barrier highly reliable and able to provide a maximum amount of energy into a hazardous location. This energy limit (even with additional safety factors applied) is known to be below the ignition point for a particular gas-air mixture, thus, guaranteeing safety for the user/operator and for the plant.