Pepperl+Fuchs KFD0-RSH-1.4S.PS2 Relay Module

The Pepperl+Fuchs KFD0-RSH-1.4S.PS2 is a single-channel relay module designed for intrinsically safe applications. It is part of the K-System interface technology family, used to transfer digital signals from hazardous areas to safe areas. The module provides galvanic isolation between the field circuit and the control circuit, as well as between adjacent channels. The output is a dry contact relay (changeover) that can switch loads up to 250 V AC / 125 V DC at 2 A. The relay can be operated in de-energized-to-safe or energized-to-safe mode. The module is certified for use in Zone 2 hazardous areas (safe area) and can be connected to intrinsically safe field devices from Zone 0, 1, or 2.

Technical Specifications

Supply voltage: 24 V DC (18-30 V). Current consumption: < 50 mA (at 24V). Input: for connection to intrinsically safe NAMUR sensors (DIN 19234) or mechanical switches. Input voltage: 8 V DC, short-circuit current approx. 8 mA. Output: relay contact (single changeover). Contact rating: 250 V AC / 125 V DC, 2 A resistive load. Response time: < 5 ms. Galvanic isolation: between input, output, and power supply (1.5 kV). Line fault detection: programmable (short-circuit and open-circuit). Ambient temperature: -20°C to +60°C. Dimensions: 20 mm (W) × 107 mm (H) × 130 mm (D). Housing: polyamide, IP20. Mounting: DIN rail (35 mm). Approvals: ATEX, IECEx, CSA, UL, SIL2 (IEC 61508).

Key Features

• Single-channel relay module for intrinsic safety barrier function

• Dry contact output (SPDT) rated 2 A / 250 V AC

• Galvanic isolation between input, output, and power supply

• Supports NAMUR sensors and mechanical switches

• Programmable line fault detection (LFD)

• Safe-state output selectable (energized/de-energized)

• ATEX / IECEx certified for use with hazardous area equipment

• DIN rail mounting, 20 mm width

Operation and Applications

The KFD0-RSH-1.4S.PS2 is typically used to transfer digital signals from sensors or switches located in hazardous areas (e.g., gas or dust environments) to a PLC or DCS in a safe area. The module limits the energy entering the hazardous area to intrinsically safe levels. The relay output can be used to drive indicators, alarms, or small actuators. The device includes line fault detection for NAMUR sensors, which can identify open-circuit or short-circuit conditions and provide diagnostic feedback.

Configuration and Wiring

The module is powered by 24 V DC (terminals 1+, 2-). Connect the field device (e.g., NAMUR proximity sensor or mechanical switch) to terminals 3 (signal) and 4 (0V). For mechanical switches, connect across 3 and 4; a series resistor may be needed. The relay output terminals are 5 (common), 6 (normally open), and 7 (normally closed). The relay can be configured for de-energized-to-safe (fail-safe) by the user's wiring. The module has DIP switches to enable/disable line fault detection and to set the safe state. All wiring should comply with local hazardous area regulations.

Safety and Standards

The KFD0-RSH-1.4S.PS2 is certified for SIL2 (IEC 61508) for use in safety instrumented functions when configured appropriately. It meets ATEX Category 3 (Zone 2) for safe area installation and can be connected to Ex ia field devices. The module has a mean time to failure (MTTF) of > 1000 years and a low probability of dangerous failure (PFD).

Maintenance

The module is maintenance-free. Check connections periodically. If the line fault LED lights, verify the field wiring. Replace the module if the relay contacts become welded or if the power supply fails.

Conclusion

The Pepperl+Fuchs KFD0-RSH-1.4S.PS2 is a compact, reliable relay interface module for intrinsic safety applications. Its galvanic isolation, line fault detection, and broad certifications make it suitable for process automation in hazardous areas.