SIRIUS S2 power contactor — 3RT1036-3BF40
The Siemens 3RT1036-3BF40 is a SIRIUS S2 power contactor rated for motor switching in AC-4 duty at 41 A on a 400 V line — that is the full-load current it can break under the hardest motor-start category (plugging, inching, reversing). For AC-2 duty (slip-ring motors, wound-rotor starting) it carries 22 kW at 400 V. At 500 V it handles 30 kW; at 690 V it drops to 11.4 kW. The coil pulls 110 V AC/DC. On the DC side the pick-up time runs 20–25 ms and the arcing time 10–15 ms — fast enough for most reversing or jogging circuits. Snaps onto 35 mm DIN rail per EN 50022; screw-type terminals on the main circuit accept solid 2x (0.25–2.5 mm²) or stranded 2x (0.75–25 mm²). Side-by-side mounting is allowed — no derating gap needed for the mechanical stack. Front face is IP20; the terminal area is IP00 — panel builders should keep live parts behind a door or cover.
Switching frequency and thermal limits
Maximum switching rate at AC-1 (resistive load) is 1,000 cycles/hour. AC-3 (standard squirrel-cage motor start/run) allows 800 cycles/hour; AC-4 (plugging/reversing) drops to 300 cycles/hour. AC-2 sits at 400 cycles/hour. Operates from -25 °C to +60 °C; storage range is -55 °C to +80 °C. Pollution degree 3 — suitable for industrial environments with conductive dust or light condensation. The contactor is rated for a 1.1× overload factor (full-scale 1.1) and a minimum permissible conductor cross-section of 16 mm² at 40 °C.
DC switching capability
For DC loads the contactor breaks 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, and 3 A at 400 V. These are the DC-1 ratings — resistive DC loads, not motor or inductive.
Lifecycle and compliance
RoHS compliance date (substance prohibition) is May 1, 2012 — the part has been fully RoHS-compliant since that date. The SIRIUS series typically carries CE, UL, CSA, and IEC certifications; verify specific approvals against the nameplate for your jurisdiction.
Sourcing and fit
This is a standard DIN-rail contactor on a 55 mm wide S2 frame, 112 mm tall, 130 mm deep. It drops into any panel with 35 mm rail and clearance for the depth — no special bracket or adapter needed.