Overview

The WEIDMULLER RSSD 800391 is a compact electromechanical interface relay module designed to provide electrical isolation and power amplification between industrial controllers (PLCs/DCS) and field devices. It allows a low-voltage control signal (typically 24 VDC) to safely switch higher voltage or current loads while protecting sensitive control electronics from surges, back EMF, and transients. Its narrow 6.2 mm design and DIN rail mounting make it ideal for high-density control cabinets, ensuring reliable operation in space-constrained applications.

Technical Data

Typical Applications

• High-Density Control Panels: Ideal for marshalling cabinets and terminal boxes requiring many I/O points in limited space.

• Solenoid and Contactor Control: Switches 120–230 VAC solenoids or motor contactors via 24 VDC PLC outputs.

• Safety Isolation: Provides galvanic isolation for safety interlocks, protecting control electronics from field faults.

• Signal Level Conversion: Safely converts control signals between different voltage levels within contact ratings.

The green LED indicates coil energization, enabling quick visual verification of relay status.

FAQ

Q1: How does the RSSD 800391's narrow width benefit control cabinet design?
A1: At just 6.2 mm wide, the module allows a higher density of I/O points on the DIN rail, saving space and reducing enclosure size in crowded control cabinets.

Q2: What protective feature is built into the coil circuit?
A2: An integrated free-wheeling diode safely dissipates high-voltage spikes (Back EMF) when the coil is de-energized, protecting PLC output transistors.

Q3: Can the RSSD 800391 switch both AC and DC loads?
A3: Yes. The relay contacts can switch AC loads up to 250 VAC and DC loads up to 125 VDC, with a maximum continuous current of 6 A. DC switching capacity is lower due to arc suppression limitations.