What it is and what it does
The Siemens 3RH1131-1HB40-ZW97 is a SIRIUS coupling relay designed for switching auxiliary circuits in control panels. It's a Size S00 device, meaning it fits the compact footprint of smaller contactors and relays in the SIRIUS modular system. The 24 VDC coil draws 2.3 W on both closing and holding, so the power supply budget is flat — no inrush spike to design around. Rated at 10 A for AC-12 duty (resistive loads in control circuits), it handles the typical auxiliary load of indicator lamps, contactor coils, and PLC inputs. The contact reliability spec — one incorrect switching operation per 100 million operations at 17 V, 1 mA — means it's trustworthy for low-energy signals like those from a sensor or a safety relay's feedback loop.
Mounting and integration
Mounts via screw or snap-on onto a DIN rail. The 45 mm width, 57.5 mm height, and 72 mm depth keep it within the S00 envelope, so it slots next to a 3RT2 contactor without crowding. The mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward and backward. That matters when you're laying out a dense panel and need to angle the relay for wire access. Terminals accept solid conductors: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm². Degree of pollution 3 means it's rated for conductive pollution environments typical in industrial control panels — no conformal coating needed for most installations. IP20 on the front protects against finger contact, standard for enclosed gear.
Electrical ratings and what they mean for your circuit
The AC-12 rating of 10 A at 24 V is the headline number for auxiliary switching, but the relay also carries rated values across a range of voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. That's the thermal current rating derating with voltage — useful if you're switching a control transformer primary or a 400 V indicator circuit. The 6 kV surge voltage resistance gives it margin against switching transients on the line side. Shock resistance is 10g / 5 ms and 5g / 10 ms, so it holds up on a machine frame or a vibrating panel door. Temperature range during operation is -25 to +60 °C, storage and transport -55 to +80 °C. The 30 million typical mechanical cycles mean it outlasts most contactors it's paired with in auxiliary duty.