Digital-Input Pulse Isolator (PR 9202A / PR 9202B)

Limit switches, proximity switches, flow and level switches and pulse outputs from meters all live in the hazardous area, and each needs an intrinsically safe interface to the control system. The PR 9202 is that interface. It supplies the intrinsically safe sensor circuit, detects the switch state or the NAMUR current level, and operates a relay on the safe side; each channel's relay can be configured normally open or normally closed and, for pulse inputs from flowmeters, follows the input at the rated frequency.

The module reads NAMUR sensors to IEC 60947-5-6 as well as plain mechanical and proximity switches, and continuously monitors the field wiring: a broken cable or a short circuit is detected and signalled separately from the switch state, so a wiring fault is never mistaken for a process condition. Extended self-diagnostics cover the module itself. One- and two-channel versions are available, powered from 19.2 to 31.2 VDC via DIN-rail terminals or the PR 9400 power rail, with the detachable PR 4500-series display for status and configuration. Protection is IP20.

Applications are pulse isolation, switch amplification, alarm monitoring and transmission of digital signals from hazardous areas in oil and gas, petrochemical, chemical, power, mining and process automation. For driving solenoids and alarms in the other direction, see the PR 9203 solenoid and alarm driver.