What it is and what it does
The Siemens 3RT1316-1BP40 is a SIRIUS power contactor in the compact Size S00 frame — 45 mm wide, 57.5 mm tall, 72 mm deep — designed for switching motor loads in control panels. It carries four normally-open main contacts and is rated 4 kW at 400 V in AC-2 duty, which covers slip-ring motor starting and reversing. The contactor mounts via screw and snap-on onto a 35 mm DIN rail per EN 50022, and the screw-type terminals accept up to 4 mm² stranded wire. The AC-2 rating (4 kW at 400 V) means it's sized for motor loads where the contactor makes and breaks both starting and running current — typical for wound-rotor motors or reversing applications. The 10 A AC-12 rating covers resistive and solid-state loads for the same contact set.
Panel fit and wiring
At 45 mm wide, this contactor fits four across a standard 600 mm-wide backpanel with room for gland plates. Side-by-side mounting is permitted, with 6 mm spacing at the side for heat dissipation. The screw terminals accept 2x (0.5 to 1.5 mm²) solid or 2x (0.75 to 2.5 mm²) stranded, or up to 2x 4 mm² with ferrules — a full range that covers control wiring and motor leads without adapters. The DC coil draws 3.3 W both on pickup and hold, so the control transformer and PLC output card see a constant load — no inrush spike to size for. Operating temperature spans -25 to +60 °C, which covers most indoor panel environments without derating.
Coordination and protection
For Type 1 coordination (no damage to the contactor under short circuit, but may need contact replacement), use a 35 A gL/gG fuse upstream. For Type 2 coordination (contactor remains operational after a fault), drop to a 20 A gL/gG fuse. The contactor is rated for pollution degree 3, meaning it's suited for industrial environments with conductive contamination. Maximum operating altitude is 2,000 m without derating — fine for most sites, but above that the air density drop reduces the contactor's interrupting capacity.