SIRIUS Size S2 Power Contactor, 30 kW at 500 V
The Siemens SIRIUS 3RT1036-3XB40-0LA2 is a Size S2 power contactor rated for 30 kW at 500 V in AC-3 duty — the motor-switching curve that governs most induction-motor loads up to that power. The 24 V DC coil pulls in at 0.7x rated (about 16.8 V) and drops out with a 20–25 ms delay, which is long enough to ride through brief sags but fast enough to clear a fault before the main breaker reacts.
Duty Ratings and Switching Frequency
This contactor carries separate switching-frequency limits per duty class: 1 000 cycles/hour at AC-1 (resistive), 800 at AC-3 (motor start/run), 400 at AC-2 (slip-ring motor), and 300 at AC-4 (plugging/inching). At 400 V AC-2 the unit is rated for 22 kW, and at 690 V AC-3 it delivers 11.4 kW. The arcing time of 10–15 ms is consistent across these loads, which helps when coordinating with upstream short-circuit protection.
The 55 mm width and 142 mm height fit a standard 8-module DIN-rail footprint, leaving room for a thermal overload relay alongside.