The DT1371 Intrinsically Safe NAMUR / Contact Isolators enable a safe area load to be controlled by a proximity detector or switch located in a potentially explosive area of zone 0 or zone 1. The units galvanically isolate the input, the output and the power supply. The safe output may be relay contact or transistor. In the case of a transistor output the maximum signal transmission frequency is 3 kHz.
The device is made in 1-channel version. In all units a built-in phase-reverse control switch allows an alarm condition (output open) to be signalled for either state of the sensor. A line-fault detection opens the output in the event of short or open-circuit lines: intended for use primerily with proximity detectors. It can also be used with switches made to resemble them electrically by adding two resistors, or disabling by a switch if not required.
A version with an input current < 0.5 mA is also available for isolation of the output contact of gas-consumption meters.
The supply voltage range is 19-29 VDC, thus the isolators are insensitive to the supply voltage change.