BEKA BA377E, Manual

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Fig 4 Typical control output application
3.2 Use with Galvanic Isolators
Galvanic isolators are probably the simplest
intrinsically safe interface to install as they provide
isolation and do not require a high integrity earth
connection.
Any galvanic isolator certified for the gas group in
which the BA377E is installed, with output
parameters less than the input parameters of the
BA377E having the correct function may be used.
Fig 5 BA377E used with galvanic isolators
Fig 5 illustrates the basic circuit that is used for all
BA377E installations protected by galvanic isolators.
Alternatively sensors may be located in the safe
area. Fig 6 shows how an additional galvanic
isolator is used to transfer the sensor output to the
BA377E in the hazardous area, although it may be
difficult to find isolators for some types of sensor.
The BA377E external input conditioning link should
be positioned to suite the output of the galvanic
isolator not the sensor.