What it is and what it does
The Siemens 3RT1374-6AP36 is a SIRIUS contactor in the Size S12 frame, designed for switching motor loads and resistive circuits in industrial control panels. It carries a 100-250 V AC coil and uses screw-type terminals on both the coil and main circuit. Rated operational currents are 4 A at 230 V, 3 A at 400 V, and 2 A at 690 V — figures that govern the real load it can handle, not a single headline number. The contactor includes two built-in auxiliary contacts (instantaneous, NO/NC configurable) and can accept up to two additional attachable auxiliary contact blocks. Mounting is via screw fixing to a vertical surface; the enclosure can be rotated ±180° and tilted forward or backward ±30° at 0° rotation. Operating temperature range is -40 to +60 °C, storage -40 to +70 °C, so it handles both cold storage and warm cabinet conditions.
Auxiliary contact ratings — the detail that matters for control circuits
The auxiliary contacts are rated for 3 A at 24 V, 1.5 A at 48 V, 0.55 A at 110/125 V, 0.3 A at 220 V, 4 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 2 A at 690 V. These are the switching limits for the control side — important when the contactor feeds a PLC input or a pilot relay. The 4 A at 230 V rating is the highest auxiliary figure; the 0.3 A at 220 V is the lowest, so verify your control voltage against the table.
Dimensions and integration
The S12 frame measures 225 mm high, 184 mm wide, and 180 mm deep. Clearance requirements: 10 mm upwards, 10 mm downwards, 20 mm forwards, and 10 mm at the side. Wire range for solid or stranded conductors is 1x (1-4 mm²) or 2x (1-4 mm²) per terminal. The screw-type coil terminals accept the same wire sizes.