SIRIUS S0 power contactor for motor switching
The Siemens SIRIUS 3RT1023-1BF40-ZX95 is a size S0 power contactor with a 110 V DC magnet coil, built for switching motor loads in control panels up to 4 kW at 400 V in AC-3 duty. Rated for 4.5 kW at 500 V and 5.5 kW at 690 V, it covers a range of line voltages common in industrial supply systems. The AC-4 rating of 8.5 A at 400 V matters for reversing or inching applications where the contactor makes and breaks stalled-rotor current.
Mounting and panel fit
Mounts by screw or snap-on onto 35 mm standard rail per DIN EN 50022, occupying 45 mm of panel width. Depth of 101 mm and height of 85 mm leave clearance for wiring duct and adjacent devices. Side-by-side mounting is permitted with 6 mm spacing at the side, which keeps the panel layout tight.
Termination and wiring
Main current circuit uses screw-type terminals accepting solid conductors 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²). Stranded conductors take 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), or max 2x 10 mm². AWG equivalents for main contacts: 2x (16 to 12), 2x (14 to 10), or 1x 8.
Coil and control circuit
Magnet coil draws 5.4 W DC for both closing and holding, so the control transformer and wiring need to support that inrush without voltage sag. Coil operates on 110 V DC; auxiliary contact ratings for DC switching are 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, and 6 A at 230 V.
Protection and coordination
For Type 2 coordination (no damage to the contactor after a short circuit), use a gL/gG fuse rated 25 A. For Type 1 coordination (contactor may need replacement), the fuse can be 63 A. Front protection is IP20 (finger-safe); terminal area is IP00 (requires enclosure protection). Pollution degree 3 rating means it's suited for industrial environments with conductive dust or condensation — standard for a panel-mounted contactor.
Environmental limits
Operating temperature range -25 to +60 °C covers most indoor and sheltered outdoor installations. Maximum operating altitude is 2 000 m without derating.