SIRIUS S12 contactor with AC coil
The 3RT1375-6AF36: It's a current-production part, so you're not chasing NOS or surplus for a new build.
Coil voltage and what it means for the panel
The pickup voltage threshold is 0.8x rated (dropout at 0.55x), so on a nominal 110 VAC control bus it picks up reliably down to about 88 V, which gives you some headroom on a sagging line. That's standard for a contactor this size — no special ferrules needed, but torque to the spec on the nameplate.
Physical fit and mounting constraints
The S12 frame measures 184 mm wide, 225 mm tall, and 180 mm deep. Mounting is by screw fixing, not DIN rail — plan for a drilled backplate or panel. These are minimums for heat dissipation and arc clearance — don't crowd it against the enclosure wall or other heat-generating devices.
Auxiliary contacts and switching capability
The contactor ships with an integrated auxiliary switch block (2 instantaneous contacts, NO/NC configurable). It can accept up to 2 attachable auxiliary switch blocks total, so you can add more feedback to a PLC or safety relay without an external terminal block. The 4 A at 230 V rating is the highest — likely the resistive load rating for that voltage class.
Environmental and switching performance
Switching times are 45-80 ms for both AC and DC operation — consistent, not fast enough for high-speed cycling but fine for motor starting and general switching.