SIRIUS S0 power contactor, 24 VDC coil
The Siemens 3RT1024-1BD44-1AA0 is a SIRIUS S0-frame power contactor rated for motor switching at 7.5 kW on 500 V and 690 V AC-3 duty, with a 24 VDC magnet coil. It carries a 12.5 A AC-4 rating for reversing or inching applications where the contactor makes and breaks stalled-rotor current. The screw-type main terminals accept up to 2x 10 mm² stranded, and the auxiliary contact block has one N/O and one N/C instantaneous contact.
What the ratings mean for your panel
The AC-3 motor rating of 7.5 kW at both 500 V and 690 V tells you this contactor handles a standard 7.5 kW induction motor across common European voltage levels without derating. The AC-4 rating of 12.5 A at 400 V governs plugging and jogging duty — if your application cycles the motor in reverse or in steps, this is the current limit that matters, not the higher AC-3 figure. The 24 VDC coil draws 5.4 W on pickup and 5.4 W holding, so it stays cool in a sealed enclosure and can be driven directly by a PLC output with a suitable free-wheel diode. For short-circuit protection, the contactor requires a gL/gG fuse rated 25 A for Type 2 coordination (no welding after a fault) and 63 A for Type 1 (welding allowed, replace the contactor). The pollution degree 3 rating means it's suitable for industrial environments with conductive dust or condensation — no derating needed in a typical panel.
Mounting and integration
The 45 mm wide S0 frame snaps onto a 35 mm DIN rail per EN 50022 or screws directly to a backplate. Side-by-side mounting is allowed with a 6 mm gap at the side for heat dissipation. The IP20 front enclosure protects against finger contact, while the terminals themselves are IP00 — standard for panel-mount contactors where the cabinet provides the overall ingress protection. Operating temperature range is -25 to +60 °C, and the maximum altitude is 2000 m without derating. The 150 mm depth fits standard 200 mm deep enclosures with room for wiring ducts.