What this contactor is and who it's for
The Siemens SIRIUS 3RT1316-2BW40 is a size S00 power contactor with a 48 VDC coil and four normally-open main contacts. It is designed for switching motor loads and resistive loads in industrial control panels, mounting on a 35 mm DIN rail per DIN EN 50022 via screw or snap-on.
Key ratings and what they mean for your circuit
The 48 VDC coil pulls 10 A at pickup and holds at 3.3 W, with a pick-up threshold of 0.85x rated voltage and drop-out at 1.1x — meaning it reliably engages at 40.8 V and stays sealed until the supply rises above 52.8 V. For motor switching in AC-2 duty at 400 V, it handles 4 kW, which covers small pumps and fans. For resistive loads (AC-1), it switches 6 A at 230 V and 3 A at 400 V. The AC-12 maximum operating current is 10 A, so it can also serve as a coupler for PLC outputs driving smaller contactor coils.
Termination and wiring
Main circuit connections use spring-loaded terminals accepting 2x (0.25 to 2.5 mm²) solid or 2x (0.25 to 1.5 mm²) fine-stranded with ferrules, or 2x (24 to 14 AWG). The IP20 protection on the front and terminals means it's safe for finger contact inside a closed panel. Side-by-side mounting is allowed with zero side clearance, so you can pack multiple units on the same DIN rail without derating for heat buildup.
Coordination and protection
For Type 1 coordination (no damage but may need replacement after a fault), use a 35 A gL/gG fuse. For Type 2 coordination (no welding and immediate reuse), use a 20 A gL/gG fuse. The contactor is rated for pollution degree 3, so it handles conductive dust and humidity typical in industrial environments. Operating temperature range is -25 to +60 °C, with a maximum altitude of 2000 m without derating.