SIRIUS vacuum contactor, size S12 — 477 A at 480 V
The Siemens 3RT1276-6LA06 is a SIRIUS vacuum contactor in the S12 frame size, rated for 477 A at 480 V. That 477 A figure governs the main pole current-carrying capacity under AC-1 duty — resistive loads at that voltage. For motor switching (AC-3), the mechanical life is rated at 10,000,000 cycles typical, and the maximum operating rate hits 750 operations per hour. The vacuum arc-quenching chamber keeps arcing time to 10 to 15 ms, which means less contact erosion and a cleaner break on inductive loads compared to an air-break contactor of the same frame.
Mounting is by screw fixing — four holes, 11 mm diameter, on a 160 mm wide by 214 mm tall footprint. Standing orientation on a horizontal surface is also permitted. That 225 mm depth includes the coil terminals, which are screw-type. For the main power circuit, stranded cable from 70 to 240 mm² is accepted. Control wiring takes solid or stranded conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or up to 2x (0.75 to 4 mm²).
Auxiliary switch and control ratings
An auxiliary switch is included as standard. Its contact ratings across the voltage range: 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, 6 A at 230 V, and 3 A at 400 V. These are the make-and-break capacities for the auxiliary circuit — useful for interlocking, status feedback, or PLC input signals.