Panel fit and ratings
The Siemens 3RT1024-1AP04-ZX95 is a SIRIUS power contactor in the S0 frame size, with three normally-open main contacts and screw-type terminals for the main current circuit. It mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022, occupying 45 mm of panel width — standard for the S0 footprint. The AC-4 rating at 400 V is 12.5 A, which governs switching of motor loads under inrush or plugging duty — the condition that stresses contacts hardest. For less severe AC-2 duty (starting and running wound-rotor motors), it handles 5.5 kW at 400 V. The AC-12 maximum operating current is 10 A, covering resistive loads in control circuits. Front protection is IP20, meaning the contactor is safe from finger contact but not sealed against dust or moisture — it belongs inside a control cabinet, not exposed to washdown. Pollution degree 3 confirms it's rated for the conductive-dust environment typical of industrial enclosures. Operating temperature range is -25 to +60 °C, and the maximum operating altitude is 2 000 m without derating. Coil data is for 50 Hz supply, with a pick-up range of 0.8 to 1.1 times rated voltage.
Termination and wiring
Main contact terminals accept 2x (1 to 2.5 mm²) stranded or 2x (2.5 to 6 mm²) multi-stranded, with a maximum of 2x 10 mm². Auxiliary contact terminals handle 2x (0.5 to 1.5 mm²) solid or 2x (0.75 to 2.5 mm²) solid, max 2x (0.75 to 4 mm²). AWG equivalents for main contacts are 2x (16 to 12) solid, 2x (14 to 10) stranded, or 1x 8. For type 2 coordination (no welding under fault), the required upstream fuse is gL/gG 25 A. For type 1 coordination (welding allowed but no fire risk), use 63 A gL/gG.