Power Supplies & Barriers

Power Supplies & Barriers

Power supplies and barriers are foundational interface modules that energize sensors and transmitters while conditioning, isolating, and - when required - making signals suitable for hazardous-area installation. In a typical 4–20 mA architecture, they provide stable loop power, protect downstream inputs, and transmit the measurement signal with galvanic isolation to reduce ground loops and noise coupling.

Their value is best seen in reliability and signal integrity. Wide-range power inputs accommodate common cabinet power standards, while isolation prevents circulating currents and shields sensitive analog signals from electrical disturbances. When installed as barriers between non-Ex and Ex zones, they enable intrinsically safe wiring concepts and help ensure that faults in the safe area cannot propagate energy into the hazardous area.

The portfolio generally includes DIN-rail power supplies for 2- or 4-wire transmitters, active barriers that combine loop power with safe separation of 4–20 mA circuits, and passive barriers used when a PLC or DCS input provides the loop energy. Options for bidirectional HART transmission, integrated HART resistors, and dedicated communication sockets support device configuration without temporary wiring. Optional HART-based monitoring can capture briefly occurring faults and translate them into relay alarms.

Typical applications include powering head-mounted temperature transmitters, isolating analog signals from field devices into multiple control or monitoring destinations, and separating loops that traverse different grounding domains. Barriers are also used to extend proven 4–20 mA/HART instrument designs into Ex-rated installations, maintaining familiar signal standards while meeting area classification requirements. In marine and utility environments, approvals and robust construction support long service life under vibration and temperature extremes.

Selection starts with loop topology (2-wire vs. 4-wire), the need for power supply vs. pure isolation, and whether the interface crosses into hazardous areas. Verify compliance with required Ex standards, SIL or marine approvals where applicable, and confirm that HART pass-through and monitoring functions align with the asset management strategy. Cabinet layout, heat dissipation, and wiring practices should be planned so the barrier modules remain accessible for commissioning and troubleshooting.

Instrumentation and Controls., an exclusive authorized representative of sales and service for Endress+Hauser.