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. It mounts via screw and snap-on onto 35 mm DIN rail per EN 50022, and its 45 mm width fits standard panel spacing for a size S0 frame.
Ratings and What They Mean for Your Load
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. The coil draws 5.4 W for both closing and holding at DC, so the control transformer and power supply need to deliver that continuously — no inrush spike beyond the holding power. Mechanical life is rated at 10 million operations typical, which is standard for a SIRIUS S0 contactor in cyclic applications.
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. For Type 2 coordination (no weld after fault), use gL/gG fuses rated 35 A; for Type 1 coordination (welding allowed), 100 A fuses are permitted.
Environmental and Mounting Conditions
Operating temperature range is -25 to +60 °C, with pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive) — suitable for most industrial control panels without additional sealing. Maximum operating altitude is 2,000 m, so no derating needed for most installations below that elevation. 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. Side-by-side mounting is permitted with a 6 mm gap required at the side for heat dissipation.