What it is and where it fits
The Siemens 3RT1025-1AH24 is a SIRIUS power contactor in the S0 frame size — the compact workhorse for motor switching in control panels up to 11 kW at 690 V (AC-3) or 7.5 kW at 400 V (AC-2). The 24 VDC coil keeps it on the standard control voltage most PLC racks and safety relays drive. Screw-and-snap mounting onto 35 mm DIN rail per EN 50022 means it drops into any panel that already carries a SIRIUS S0 footprint; no adapter plates needed.
What the ratings mean for the buyer
The headline 11 kW at 690 V (AC-3) is the motor-switching rating — sized for a standard 11 kW three-phase induction motor on a 690 V line. At the more common 400 V supply, the AC-3 rating drops to 10 kW. The AC-4 rating of 15.5 A at 400 V covers inching and plugging duty where the contactor makes and breaks stalled-rotor current; if your application cycles the motor under load repeatedly, that 15.5 A figure governs contact life, not the 11 kW AC-3 number. The 24 VDC coil holds at nominal and drops out below roughly 18 V, which is typical for this class — verify your control supply doesn't sag under load.
Panel fit and wiring
At 45 mm wide, 85 mm tall, 140 mm deep, the S0 frame fits a standard 45 mm DIN slot — four of these sit side-by-side in a 180 mm wide section without forced spacing. The screw terminals accept 2x (0.5…1.5 mm²) solid or 2x (0.75…2.5 mm²) stranded on the control side, and 2x (1…2.5 mm²) or up to 2x 10 mm² on the main circuit. That covers most motor feeder cables up to 4 mm² per phase. IP20 on the front means finger-safe in the cabinet; the terminal area itself is IP00 — keep tools and fingers clear when live.
Environmental limits
Rated for operation from -25 °C to +60 °C — fine for most indoor panel environments, including unheated warehouses. Pollution degree 3 means it tolerates conductive dust and occasional condensation; still, keep it in a sealed cabinet if the atmosphere is gritty or damp. Maximum altitude 2000 m without derating; above that, consult the thermal curve.