Siemens SIRIUS 3RT1026-1BD40-1AA0 — Power Contactor, Size S0
The Siemens SIRIUS 3RT1026-1BD40-1AA0 is a size S0 power contactor rated for motor switching at 11 kW in AC-2 duty at 400 V, and the same 11 kW at both 500 V and 690 V — meaning it handles the same motor load across standard European supply voltages without derating the power rating.
The AC-2 rating of 11 kW at 400 V is the key figure for slip-ring motor duty — AC-2 covers starting and plugging of wound-rotor motors, where the contactor sees higher switching frequency than a standard AC-3 squirrel-cage start. For AC-4 reversing or inching duty, the contactor is rated 15.5 A at 400 V. In AC-12 (resistive) service, the maximum operating current is 10 A, suitable for switching heater banks or transformer primaries within that limit.
Wiring and Terminal Data
Main current circuit terminals are screw-type, accepting 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), or max 2x 10 mm² stranded — or 2x (16 to 12), 2x (14 to 10), 1x 8 AWG. Auxiliary contact terminals accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²) solid.
Environmental and Mounting Conditions
Front of the device carries IP20 protection (finger-safe), while the terminals themselves are rated IP00 — meaning the wiring area is not touch-safe without the panel enclosure providing the final protection.