What it is and where it fits
The Siemens 3RH2131-1VB40 is a SIRIUS coupling relay — a contactor-style device for switching auxiliary circuits in control panels. It carries 3 normally-open instantaneous contacts rated 10 A at 24 V and 10 A at 230 V, with a 24 VDC coil drawing 1.6 W. The size S00 housing snaps onto 35 mm DIN rail or screws directly to a panel backplate.
What the ratings mean for your panel
The 10 A rating at both 24 V and 230 V covers most auxiliary loads — pilot lights, solenoid valves, small contactor coils. The 3 NO contacts give you three independent switching paths in one package, which saves DIN-rail space compared to stacking individual relays. The diode surge suppressor is built into the coil circuit, so you don't need an external flyback diode on the DC side. Mounting is flexible: screw-fix or snap onto 35 mm DIN rail. The 45 mm width and 73 mm depth fit standard enclosure layouts. Clearances: 10 mm upward and forward, 6 mm at the sides. Operating temperature range is -25 to +50 °C, storage -55 to +80 °C.