Answer / haridass

Barriers are used in Hazardous locations to power Intrinsic
Safe instruments. The barrier will reduce the available
loop current to a level that cannot produce a spark.

An Isolator is used to connect signals of different common
mode voltage for example a transmitter signal may be
referenced to +24 whereas the DCS may be referenced to
ground.

You can also have an isolator that is designed for use in
Intrinsic Safe circuit.

Regards
Roy (http://www.control.com/thread/1230701520)

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