What this contactor is and what it does
The Siemens SIRIUS 3RT1035-1BB44-3MA0 is a size S2 power contactor rated for motor switching at 22 kW on 500 V and 11.4 kW on 690 V. It uses screw-type terminals for the main current circuit and mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 50022. This is a current-production part, not a phase-out or obsolete item.
Mounting and panel fit
At 55 mm wide, 112 mm tall, and 179 mm deep, this contactor fits standard S2 panel cutouts. Side-by-side mounting is supported, so you can gang multiple units without extra spacing. The front face carries an IP20 rating for basic finger-safe touch protection inside the enclosure, while the terminal area is IP00 — keep live parts behind a door or cover.
Electrical ratings and what they mean for your load
The AC-3 motor rating of 22 kW at 500 V and 11.4 kW at 690 V tells you the contactor can handle full-load starting and running of standard induction motors at those voltages. For heavy-duty jogging or reversing (AC-4 duty), it's rated 35 A at 400 V — a lower continuous current than AC-3, reflecting the stress of inching and plugging. The AC-2 rating (slip-ring motors) is 18.5 kW at 400 V. Maximum switching frequencies vary by duty: 1 200 cycles/hour for AC-1 (resistive), 1 000 for AC-3, and 300 for AC-4 — so don't expect this part to run a high-speed pick-and-place solenoid at 3 000 cycles/hour.
Coil and control circuit
The coil is 24 V DC rated. Holding current at 24 V is 10 A; at 60 V it drops to 2 A, at 110 V to 1 A, and at 220 V to 0.3 A. For AC coils, expect 6 A at 230 V and 3 A at 400 V. Arcing time is 10 to 15 ms; DC dropout is 20 to 25 ms. These numbers matter for timing coordination with upstream PLC outputs or safety relays — the dropout delay is long enough that you'll want to sequence power removal if you're relying on fast contact opening.
Termination and wiring
Main circuit terminals accept solid conductors from 2x 0.5 mm² up to 2x 4 mm², and stranded from 2x 0.75 mm² up to 25 mm². The solid-or-stranded range is 2x 0.75 to 16 mm². At 40 °C, the minimum permissible conductor is 16 mm² — that's the thermal derating floor, not a wiring limit. For control wiring, solid conductors from 0.5 to 1.5 mm² and stranded up to 2.5 mm² are typical. Screw terminals mean you'll need a torque driver on site, not a spring-cage tool.
Environmental and compliance
Operating temperature range is -25 to +60 °C; storage extends from -55 to +80 °C. Pollution degree 3 means it's designed for industrial environments with conductive contamination — no extra conformal coating needed for most panel conditions. RoHS compliance substance prohibition date is May 1, 2012, so it meets current EU RoHS requirements. Mechanical life is typical 10 million operations.