What this coupling relay does that a standard contactor cannot
The 3RH2140-2SB40 is a SIRIUS coupling relay purpose-built for switching auxiliary circuits — not main motor loads. Its 4 NO instantaneous contacts are rated 10 A at both 24 V rated value and 230 V rated value, covering the signal-level switching that a power contactor's aux contacts typically cannot handle at lower voltages without derating.
Panel fit and DIN-rail integration
Size S00 frame with a footprint of 45 mm width, 70 mm height, and 73 mm depth.
Coil and surge suppression — what the 24 VDC rating means for the control loop
Rated coil voltage is 24 VDC, with a closing power of 1.6 W. The integrated suppressor diode clamps the inductive kickback on de-energisation — no external flyback diode needed across the coil.