What it is and what it does
The Siemens 3RT1316-1BD40 is a SIRIUS power contactor in the S00 frame size, designed for switching motor loads in control panels. It carries four normally open main contacts, rated for 4 kW at AC-2 duty on a 400 V supply — that's the motor switching rating for slip-ring or wound-rotor motors, where the inrush isn't as brutal as AC-3. For resistive loads (AC-12), it handles up to 10 A. The coil is a DC-operated type, pulling 3.3 W on both close and hold, so the control transformer sizing is straightforward.
Mounting and integration
Mounts via screw or snap-on onto a 35 mm DIN rail per EN 50022 — standard panel fare. The 45 mm width and 57.5 mm height fit the S00 footprint, and side-by-side mounting is allowed with 6 mm spacing to adjacent devices for heat dissipation. The operating temperature range is -25 to +60 °C, and it's rated for pollution degree 3, meaning it's fine in industrial enclosures where conductive dust or condensation might be present. The IP20 finger-safe protection on the front and terminals is typical for enclosed panel use.
Termination and wiring
Main circuit terminals are screw-type, accepting solid or stranded copper: 2x 0.5–1.5 mm², 2x 0.75–2.5 mm², or max 2x 0.75–4 mm². For AWG, that's 2x 20–16, 2x 18–14, or 1x 12. Finely stranded wire with ferrule is also supported in the same ranges. The DC coil terminals follow the same wire size specs. For short-circuit protection, Type 2 coordination (no welding) requires a gL/gG 20 A fuse; Type 1 (welding allowed, no fire) allows up to 35 A gL/gG.
Switching capacity across voltages
The contactor's switching capacity varies by voltage for DC loads: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V. For AC loads at 230 V it's 6 A, and at 400 V it's 3 A. These are the make-and-break ratings for the main contacts, not continuous carry — the AC-12 rating of 10 A is the continuous resistive current limit.