SIRIUS S0 power contactor — 24 VAC coil, 10/11 kW motor duty
The Siemens 3RT1025-1AC24-0AA1-ZX95 is a SIRIUS S0-frame power contactor with a 24 VAC 50/60 Hz coil, designed for screw and snap-on mounting onto 35 mm standard mounting rail per DIN EN 50022. It is rated for motor switching at 10 kW at 500 V and 11 kW at 690 V, covering common 400 V and 690 V industrial supply voltages across Europe and export markets. The S0 frame (85 mm height, 45 mm width, 140 mm depth) fits standard 45 mm-wide DIN-rail slots — one module per contactor. Side-by-side mounting is permitted, so a multi-contactor motor starter or reversing group packs tightly on the rail with no mandatory air gap.
Ratings that drive the spec decision
For plugging or inching duty (AC-4 at 400 V), the contactor is rated 15.5 A, which governs applications like crane hoists or reversing conveyors where the motor is reversed under load. For resistive loads (AC-12), the maximum operating current is 10 A. The auxiliary contact ratings span 10 A at 24 V down to 0.3 A at 220 V — enough for PLC-level signal switching but not for heavy pilot duty above 220 V. The coil holds at 24 VAC with a tolerance range of 0.8...1.1 at 50 Hz and 0.85...1.1 at 60 Hz. Below the dropout threshold the contactor releases; a brownout below 19.2 VAC at 50 Hz will drop the main contacts.
The main current circuit uses screw-type terminals accepting 2x (0.5...1.5 mm²), 2x (0.75...2.5 mm²), or max. 2x (0.75...4 mm²) solid/stranded. For larger conductors, the terminal also takes 2x (1...2.5 mm²) and 2x (2.5...6 mm²) single or multi-stranded, with a maximum of 2x 10 mm². AWG equivalents are 2x (16...12), 2x (14...10), and 1x 8. With type of coordination 2 (no welding after short circuit), a gL/gG 25 A fuse is required upstream. With type 1 coordination (welding allowed but no fire risk), a 63 A fuse is needed. The contactor itself has 2 instantaneous auxiliary contacts. The mechanical service life is typically 10 million operations.