The Siemens 3RQ4052-1SM50 is an output optocoupler relay from the SIRIUS 3RQ4 family of coupling relays in a narrow 6.2 mm housing. It provides galvanic isolation between a 24 V DC control signal and a single normally-open (NO) contact rated for a thermal current of 2 A, terminated via screw terminals. This form factor is designed for dense DIN-rail mounting in control panels where space is at a premium — the 6.2 mm width allows high channel counts per linear meter of rail. The optocoupler input means the coil side draws minimal current from the 24 V DC supply, making it suitable for PLC digital output cards with limited per-channel drive capability.
Compliance and regulatory documentation
The 3RQ4052-1SM50 is RoHS compliant since 26 September 2024, and carries a REACH Article 33 duty-to-inform notification for lead (CAS 7439-92-1) above 0.1% w/w in the product.
Integration notes for the controls engineer
The 6.2 mm width and screw terminal design suit panel layouts where terminal-block density is already high. The 24 V DC coil operates from standard PLC output voltages, and the 2 A thermal current rating covers signal-level switching for solenoid valves, contactor coils, and indicator loads within that current envelope. Because it is an optocoupler relay, there is no mechanical coil to wear out — switching life is effectively limited by the output contact rating. For cold-storage or refrigeration panel environments, the sealed optocoupler input side avoids condensation issues that can plague electromechanical relay coils in sub-zero enclosures.