SIRIUS S2 power contactor — 3RT1034-1AH04
The Siemens 3RT1034-1AH04 is a SIRIUS power contactor in size S2, rated for motor switching at 18.5 kW at 500 V AC-3 and 10 kW at 690 V AC-3.
At 55 mm wide, 112 mm tall, and 164 mm deep, the S2 frame fits standard 55 mm-wide contactor slots in motor control centers. The 18.5 kW AC-3 rating at 500 V governs motor switching for pumps, fans, and compressors up to that load; the 10 kW rating at 690 V applies where line voltage runs higher. AC-4 at 400 V is rated 29 A — that's the inching or plugging duty cycle, not continuous running. The 50 Hz operating range of 0.8 to 1.1 times rated voltage means the coil holds in on a sagging line down to about 38 V for a 48 V coil.
Wiring and terminal capacity
Screw terminals accept solid conductors from 2x 0.5 mm² up to 2x 4 mm², and stranded from 2x 0.75 mm² up to 2x 25 mm². For the main circuit, solid or stranded wire from 0.75 mm² to 16 mm² is accepted. At 40 °C ambient, the minimum permissible conductor cross-section is 16 mm² — that's the thermal derating floor for full rated current. Side-by-side mounting is allowed with no derating penalty, which simplifies panel layout.
Switching rates and mechanical life
Maximum switching rates: 1,200 cycles/hour at AC-1 (resistive), 750 at AC-2 (slip-ring motors), 1,000 at AC-3 (squirrel-cage motors), and 250 at AC-4 (inching/plugging). Arcing time runs 10 to 15 ms; operating time at AC is 7 to 20 ms.