Intrinsic safety barriers for hazardous areas

Paul Boughton

Designing control systems for explosive environments can be a challenging task.

Whether handling flammable liquids, gases, or powders, you need to ensure that your control components can safely operate in these environments.

Although there are several methods for designing these systems, a common one is designing to Intrinsic Safety (IS) Standards. This means that components used in these areas are designed and operated to limit the amount of energy used. This keeps the component operation below the threshold ('lower explosive limit' or LEL) at which the hazardous material will explode.

An intrinsically safe control systems needs to include both an intrinsically safe encoder and an Intrinsic Safety Barrier. Used together, they comprise a system that avoids an explosion by limiting voltage and current. This pairing constitutes a solution to operation in Class I and Class II Division 1 hazardous environments.

Intrinsic Safety Barriers provide both power and signal isolation for an incremental encoder with differential quadrature outputs and an index. This all-in-one approach saves the cost and inconvenience of buying separate power and signal barriers as required by other systems.

A barrier which is galvanically isolated will also save the added cost of maintaining a high integrity earth ground.

BEI Industrial Encoders is based in Goletta, CA, USA. www.beiied.com

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