What it is and what it does
The Siemens SIRIUS 3RT1026-1CC24 is a size S0 power contactor with a 24 VAC coil rated for both 50 Hz and 60 Hz supply. It switches motor loads up to 11 kW at 400 V in AC-3 duty, which covers the vast majority of standard three-phase induction motors in that power band — pumps, fans, small conveyors, compressors. The coil tolerance spans 0.8 to 1.1 times rated voltage at 50 Hz and 0.85 to 1.1 at 60 Hz, so it holds in through brownout conditions that would drop out a tighter-coil contactor. Mounting is screw-and-snap-on onto 35 mm DIN rail per EN 50022, the standard for panel integration. The 45 mm width (three module spaces) and 88 mm height fit the S0 footprint common across the SIRIUS contactor family, so panel layout and busbar planning are straightforward if you're replacing or expanding an existing SIRIUS installation.
Key ratings and what they mean for fit
The AC-3 rating of 11 kW at 400 V is the headline motor-switching figure — it tells you the contactor can make and break a squirrel-cage motor at full load without excessive contact wear. For resistive loads (AC-1), the maximum operating current is 10 A. The AC-4 rating of 15.5 A at 400 V covers plugging and inching duty, where the contactor must interrupt locked-rotor current; if your application cycles the motor against a stopped load, that's the number to watch. The auxiliary contact block is a 2-pole instantaneous contact (NO/NC configurable by wiring). The integrated varistor surge suppressor on the coil means you don't need an external RC snubber for standard 24 VAC control circuits — it handles the inductive kick internally, saving a component and a wiring step. Termination is screw-type for the main circuit, accepting 2x (1 to 2.5 mm²) or 2x (2.5 to 6 mm²) solid/stranded, with a maximum of 2x 10 mm². The control circuit terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²), up to 4 mm² max. That covers standard panel wire sizes without adapters. Degree of pollution 3 means the contactor is rated for conductive pollution environments — typical in industrial enclosures where dust, oil mist, or light condensation are present. IP20 on the front, IP00 at the terminals: the body is touch-safe, but the wiring terminations need enclosure protection.