The Siemens 3RQ4038-1AF01 is a SIRIUS 3RQ4 coupling relay in the narrow 6.2 mm housing. It takes a 230 V AC/DC control signal on the input side and switches one change-over contact rated for 6 A thermal current. The hard gold-plated contacts handle low-level signals reliably — that plating matters when you're switching dry circuits or PLC-level logic where standard silver contacts would oxidize and fail to make contact.
At 6.2 mm wide, it takes up one module slot — useful when you're packing multiple isolation points into a tight enclosure. The narrow design means you can fit roughly 16 of these per 100 mm of rail, which matters for panel fill factor.
Compliance and regulatory
RoHS compliant since September 2024. Export control is straightforward: AL N / ECCN EAR99, no special licensing required.