SIRIUS Size S0 Power Contactor, 24 VDC Coil
The Siemens 3RT2024-2FB44-3MA0 is a SIRIUS-brand power contactor in the Size S0 frame, designed for switching motor and resistive loads in industrial control panels. It carries a 24 VDC coil and uses spring-type terminals for the main and control wiring, which simplifies panel wiring and reduces maintenance compared to screw terminals. Rated for motor duty at 2 hp on a 230 V supply, the contactor handles the inrush and running current of small induction motors — typical for pumps, fans, and conveyors in a production line. The main contact configuration is 18...8 A, meaning the normally-open main poles are rated for that current range under AC-3 duty. The coil draws 6 A at 24 V rated value during pickup, then holds at a lower sealed current. Switching times are 15...17.5 ms for DC operation, with an arcing time of 10...10 ms — fast enough for most sequencing applications but worth noting if your safety circuit requires a specific off-delay.
Mounting and Integration
Mounts via screw or snap-on onto a 35 mm DIN rail per DIN EN 60715, the standard for European control panels. The Size S0 footprint — 45 mm wide, 102 mm tall, 154 mm deep — fits standard enclosure layouts; plan for the depth when routing wiring behind the panel. Mounting position is flexible: the contactor can be rotated ±180° on a vertical surface and tilted forward/backward by ±22.5°, which helps when fitting into tight or angled sub-panels. Clearance requirements are 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side — tight enough for dense DIN-rail packing but leave the side gap for heat dissipation. Spring-type terminals accept solid or stranded wire from 1 to 10 mm², or two conductors of 0.5 to 2.5 mm² each. No special tools beyond a screwdriver for the spring release — faster to wire than screw clamps and less prone to loosening under vibration.
Duty Ratings and Thermal Limits
Switching frequency reaches 1 000 operating cycles per hour under AC-1, AC-2, AC-3, and AC-3e duty, and 300 cycles per hour under AC-4 (plugging/inching). The mechanical endurance is 10 000 000 operations typical, so the contactor is built for high-cycle applications like conveyor indexing or press control. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. The operating factor has an initial value of 0.8 and a full-scale value of 1.1. The contactor has no built-in auxiliary switch, so if you need feedback contacts for a PLC input or status indication, you will need to add a separate auxiliary contact block that fits the S0 frame.