What it is and what it does
The Siemens 3RT1036-1AK64-3MA0 is a SIRIUS power contactor in Size S2, built for switching motor loads in control panels. It's rated for 22 kW at AC-2 duty on 400 V, and can handle 30 kW at 500 V or 11.4 kW at 690 V, so it covers a solid range of three-phase induction motors across common European and North American supply voltages. The contactor mounts on a 35 mm DIN rail per EN 50022, either snapped on or screwed down, and takes screw-type terminals on the main circuit. At 55 mm wide, it fits a standard panel slot without crowding adjacent devices. It's rated for both 50 Hz and 60 Hz supply, with an operating factor of 0.8 to 1.1 at either frequency. The mechanical service life is listed at 10,000,000 operations.
What the key ratings mean for fit
The AC-2 rating at 400 V (22 kW) is the one that governs motor switching for slip-ring or wound-rotor motors — it's not the same as the AC-3 rating for cage motors. If your line has a motor starting under load or reversing frequently, AC-2 is the duty class you need, and this contactor delivers it. The auxiliary contact block handles 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V, so it can drive smaller relays or PLC inputs directly without an interposing relay in most panels. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. Pollution degree 3 means it's fine in industrial environments with conductive dust or occasional condensation — no need for a sealed enclosure unless the atmosphere is aggressive. The front face is IP20 (finger-safe), while the terminals are IP00 — that's normal for panel-mount contactors; the enclosure provides the terminal protection.
Sourcing and lifecycle reality
For a line-down replacement, this is a direct drop-in for any panel originally built with a Size S2 SIRIUS contactor on a 35 mm DIN rail. The screw terminals accept solid wire from 0.5 to 4 mm² and stranded up to 25 mm², so re-terminating existing cables is straightforward.
Wiring and integration notes
Screw terminals on the main circuit accept 2x (0.75 to 25 mm²) stranded, or 2x (0.5 to 4 mm²) solid. The auxiliary terminals take 2x (0.75 to 16 mm²) solid or stranded. That covers most panel wiring from control to power feeds without needing adapters. Side-by-side mounting is allowed, so you can gang multiple contactors on the same rail without a gap — useful for grouping motor starters in a compact MCC section.