What this contactor is and where it fits
The Siemens SIRIUS 3RT1024-3EL24-0KS0-ZX95 is a power contactor in the S0 frame size, designed for switching motor loads up to 7.5 kW at 690 V (AC-3 duty) and 5.5 kW at 400 V in AC-2 use. It mounts on a 35 mm DIN rail per EN 50022 or screws directly into the panel — the 45 mm width and 140 mm depth leave room for adjacent devices in a crowded enclosure. The contactor carries an integrated RC surge suppressor across the coil, which saves you an external snubber on inductive loads like motor starters or solenoid valves. The front face is rated IP20 (finger-safe), and the terminals themselves are IP00 — standard for a panel-mount power device. Side-by-side mounting is allowed without derating for the thermal current, so you can pack multiple contactors on the same DIN rail for multi-motor groups. The operating temperature range of -25 to +60 °C covers most indoor control panels, even those near hot machinery.
Key ratings and what they mean for the buyer
The AC-3 motor-switching rating of 7.5 kW at 690 V (or 7.5 kW at 500 V) tells you this contactor handles a standard 10 HP motor at 480 V and a 7.5 kW motor at 690 V. The AC-4 rating of 12.5 A at 400 V covers inching and plugging duty where the contactor makes and breaks the motor at full locked-rotor current. For resistive loads (AC-12), the maximum operating current is 10 A. The auxiliary contact block is rated for 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V — so it can switch a PLC output or a small relay coil without a separate interposing relay. The screw terminals accept solid conductors from 0.25 to 2.5 mm² (two per clamp) and stranded up to 6 mm², with a maximum of 10 mm² per terminal. The recommended fuse for type 2 coordination is a 25 A gL/gG — this limits fault energy so the contactor survives a short circuit without welding.
Lifecycle and sourcing reality
Because it's an active part, there's no urgency to stockpile or find a substitute. If you're specifying it into a new design, the S0 frame size and 45 mm width are common across the SIRIUS contactor family, so panel layout and wiring practice carry over to other ratings.