SIRIUS 3RT1034-3AC20 — Power Contactor, Size S2
The Siemens SIRIUS 3RT1034-3AC20 is a size S2 power contactor rated for 15 kW in AC-2 duty at 400 V — the utilisation category for slip-ring motor starting and reversing, where the contactor makes and breaks the rotor current at reduced voltage. Per the datasheet, the mechanical life is typical 10 million operations; the electrical life at AC-3 duty is rated at 1 000 switching cycles per hour maximum, and at AC-4 (plugging/inching) it drops to 250 cycles per hour.
The enclosure face carries an IP20 rating (finger-safe terminals on the front); the terminal area itself is rated IP00, meaning the wiring compartment is open to the panel environment — standard practice for enclosed contactor panels, but something to note if you're running this in a dust-prone cabinet without a separate enclosure.
Wiring and Terminal Data
Main current circuit terminals are screw-type. Solid conductors: 2x (0.25... 2.5 mm²). Stranded conductors: 2x (0.75... 25 mm²). The 25 mm² upper end on stranded is generous for a size S2 — it accommodates larger cable lugs without a terminal reducer. Depth is 115 mm, width 55 mm, height 112 mm; the 55 mm width matches the standard S2 footprint, so panel cut-outs and gland-plate planning are straightforward.