What it is and what it does
The Siemens SIRIUS 3RT1373-6AP36 is a size S12 contactor with an AC coil rated for 100... 250 V at 50/60 Hz. It carries two normally-open instantaneous auxiliary contacts rated at 4 A at 230 V, 3 A at 400 V, and 2 A at 690 V — these are the standard utilization categories for control-circuit switching, not main power contacts. The coil pull-in and drop-out times are 45... 80 ms on AC or DC, which is typical for a contactor this size and means it coordinates cleanly with upstream protective devices during a fault sequence. This is a main contactor for motor or resistive loads, not an auxiliary relay — the S12 frame is designed for switching currents up to the contactor's rated operational current (not listed here, but the frame class implies a motor rating in the 50-70 A range at 400 V). The 100-250 V AC coil covers most European and North American control voltages without a separate transformer tap.
Mounting and integration
Mounts via screw fixing on a vertical surface, with ±180° rotation and ±30° tilt forward or backward at 0° rotation. That flexibility helps when retrofitting into an existing panel where the backplate is already drilled — you can orient the contactor to line up with pre-existing bus bars or wiring ducts. Clearance: 10 mm upwards, 10 mm downwards, 10 mm at the side, 20 mm forwards — tight enough for a standard 600 mm deep enclosure. Dimensions: 184 mm wide, 225 mm high, 180 mm deep. That's a substantial footprint — the S12 frame is the largest standard contactor size in the SIRIUS family, so plan for a 300 mm wide DIN-rail section or a dedicated sub-panel. The screw-type coil terminals accept 1x or 2x conductors from 1 to 4 mm² solid or stranded.
Environmental tolerance
Rated for -40 to +60 °C during operation and -40 to +70 °C during storage. That -40 °C low end matters for cold-weather installations — unheated pump houses, outdoor MCCs in northern climates, refrigerated warehouses. The storage range covers extended downtime in unheated warehouses.