The Siemens 3RQ4055-2SM30 is an output optocoupler relay from the SIRIUS 3RQ4 family, built in the narrow 6.2 mm housing for high-density cabinet layouts. It switches a single normally-open contact rated for a thermal current of 6 A, driven by a 24 V DC control signal. The optocoupler input gives galvanic isolation between the PLC or controller output and the load circuit — useful when you need to break ground loops or protect a 24 V DC digital output from a separate power domain.
Lifecycle and compliance posture
This part carries an active lifecycle status — Siemens lists it as current production, so no last-time-buy or obsolescence pressure on the BOM line. RoHS compliance is confirmed effective 26 September 2024, and the REACH candidate list declaration flags lead (CAS 7439-92-1) above 0.1% w/w, which is a standard disclosure for electronic components with solder joints. Export classification is AL: N / ECCN: EAR99, meaning no special licensing for most destinations.
Sourcing decision
Because it's an active, standard-product-class item (class A), the 3RQ4055-2SM30 is a straightforward line-item to specify into a BOM. The 6 A thermal current and 24 V DC coil are common values, so the part slots into control panels without special coordination. For a firm commitment, submit an RFQ — this is a quoted-to-order line, not a shelf-pick gamble.