The Siemens 3RQ4118-1AM01 is an output coupler with a plug-in relay from the SIRIUS 3RQ4 family, designed for narrow control-panel integration. Its 6.2 mm width packs a single change-over contact into a DIN-rail footprint, which matters when you're squeezing I/O density into a crowded enclosure — every millimeter of rail space counts. The 6 A thermal current rating (Ith) defines the continuous current the contact can carry in resistive or lightly inductive circuits; it is not a motor-switching rating, so size it for signal-level loads or small contactors, not direct motor starts.
Deployment context and contact metallurgy
The hard gold-plated contacts are specified for low-level switching — think PLC outputs, sensor signals, or control-voltage circuits where oxide films on standard silver contacts would block milliampere-level currents. This part sits in the signal chain, not the power path. The 24 V DC coil is standard for 24 VDC control systems; verify your control voltage matches before wiring.
Panel integration — what the 6.2 mm width buys you
At 6.2 mm per unit, you can mount roughly 16 of these on a standard 100 mm DIN-rail segment. The narrow design is the defining feature for panel builders: it lets you cluster coupling relays next to the I/O modules they serve, keeping wiring runs short and the cabinet layout logical. The plug-in relay means the base stays wired when you pull the relay for replacement — no re-termination during troubleshooting or spare swap.