What it is and what it does
The Siemens 3RT1026-1BE40 is a SIRIUS S0-frame power contactor. It's built for switching three-phase motors in a control panel — screw and snap-on mount onto a 35 mm DIN rail per EN 50022, so it lands in the same footprint as any standard S0 contactor. Rated motor power is 11 kW at 500 V and also 11 kW at 690 V under AC-3 duty — that's the rating that governs motor starting. For inching or reversing (AC-4), it handles 15.5 A at 400 V. The AC-2 rating at 400 V is also 11 kW, covering slip-ring motor applications. The coil is DC-operated, drawing 5.4 W for both closing and holding — no power drop once sealed, which simplifies the DC supply sizing in the panel.
Ratings that decide the fit
The 45 mm width (S0 frame) is the panel-space number. It's the same width as other S0 contactors, so a panel laid out for a 3RT1015 or 3RT1034 will accept this one without re-drilling the DIN rail or re-routing the main power cables. The main circuit uses screw-type terminals, accepting solid wire from 2x 0.5 mm² up to 2x 4 mm², or stranded up to 2x 10 mm². That's enough for the motor leads on an 11 kW load at 500 V — no need for crimp ferrules if you're running solid conductors. Type 2 coordination (no damage to the contactor on a short circuit) requires a 35 A gL/gG fuse upstream. Type 1 coordination (contactor may need replacement after a fault) allows a 100 A fuse. That's the selectivity decision for the panel builder. Rated operating temperature is -25 to +60 °C, with a maximum operating altitude of 2000 m. Pollution degree 3 means it's suited for industrial environments with conductive dust or occasional condensation — not clean-room, but standard for a motor control centre.
What the ratings mean for the buyer
The 11 kW at 500 V AC-3 rating is the one that decides if this contactor fits a given motor. It's not the absolute maximum current — that's 10 A at AC-12 (resistive) — but the motor-switching capability under inductive load. For a 500 V motor, 11 kW is roughly 16 A full-load current, so the contactor is sized with some headroom above that. The auxiliary contact ratings cover the control circuit: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V DC. That last one matters for DC control buses — many contactors have derated DC ratings, and this one is no exception.