What it is and what it does
The Siemens SIRIUS 3RT1023-1AL20-ZW96 is a size S0 power contactor rated for switching motor loads and resistive circuits in control panels. It carries a 10 A rated operational current at 24 V and can handle up to 5.5 kW at 690 V. The front face is IP20, while the terminal area is IP00 — standard for panel-mounted contactors where the enclosure provides the final ingress protection. Screw-type terminals on the main circuit accept solid conductors from 2x (0.5 to 1.5 mm²) up to a maximum of 2x (0.75 to 4 mm²), and stranded conductors from 2x (1 to 2.5 mm²) up to a maximum of 2x 10 mm². That covers most panel wiring up to about 10 AWG.
Mounting and integration
Mounts via screw or snap-on onto a 35 mm standard mounting rail per DIN EN 50022. The 45 mm width and 91 mm depth fit the S0 footprint — a common size in Siemens SIRIUS family panels. Side-by-side mounting is allowed, with a 6 mm clearance required at the side for heat dissipation. Operates from -25 to +60 °C ambient, pollution degree 3, and is rated for use up to 2 000 m altitude. That covers most indoor industrial environments without derating.
Switching ratings and coordination
The contactor is rated for AC-2 duty at 4 kW at 400 V and AC-4 duty at 8.5 A at 400 V — the AC-4 figure is the one that matters for reversing or plugging duty where the contacts break under load. For type 2 coordination (no weld risk), use a gL/gG fuse rated 25 A; for type 1 coordination (welding allowed but no fire risk), a 63 A fuse is permitted. Mechanical life is rated at 10 million operating cycles typical. The coil operates at 50/60 Hz with a voltage tolerance of 0.8 to 1.1 times rated at 50 Hz, and 0.85 to 1.1 at 60 Hz.