The Siemens 3RT1276-6AP36-0KA1 is a SIRIUS vacuum contactor in the S12 frame size. The vacuum switching technology means the arc is extinguished in a sealed bottle, giving it a mechanical service life of 10,000,000 operations typical. The coil is rated 220-240 V AC and terminates in screw-type terminals. The main circuit accepts stranded conductors from 70 to 240 mm² — sized for the S12 frame's current-carrying capacity. Auxiliary wiring accepts 2x (0.5 to 1.5 mm²) solid or 2x (0.75 to 2.5 mm²) stranded, with a maximum of 2x (0.75 to 4 mm²).
At 214 mm high, 160 mm wide, and 225 mm deep, the S12 frame is a substantial piece of iron — plan the gland plate and DIN-rail clearance accordingly. The depth of 225 mm is the dimension that most often surprises panel builders who are used to IEC 60947-4-1 contactors in smaller frames.
The auxiliary contact ratings are given at specific control voltages: 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, and 1 A at 110 V — these are the switching capacities for the built-in auxiliary switch, not the main pole ratings.