Vacuum Contactor for Medium-Voltage Switching
The Siemens SIRIUS 3RT1276-6AS36 is a vacuum contactor in size S12, rated for switching at 500 to 550 V AC. The vacuum arc-quenching chamber means it handles medium-voltage motor loads without external arc chutes — cleaner switching and less maintenance than air-break contactors in the same footprint. Rated for 10 A at 24 V DC on the auxiliary contacts, with lower ratings at higher voltages: 2 A at 48 V or 60 V, and 1 A at 110 V. That auxiliary capacity covers most PLC or relay interposing loads without an extra interface relay.
Mounting and Mechanical Fit
Fastens via screw fixing (two 11 mm holes on 160 mm width, 214 mm height, 225 mm depth). That 20 mm forward gap is the one that catches people — factor it into the enclosure depth before routing the main power cables.
Maximum switching rates: 750 operations per hour under AC-3 (motor starting) or AC-3e duty, 700 ops/h under AC-1 (resistive), and 250 ops/h under AC-2 or AC-4. The AC-4 rate matters for reversing or inching applications — that's the limiting case for jogging duty.