SIRIUS Size S0 power contactor — what fits in the panel
The Siemens 3RT2027-1AN20-0UA0 is a SIRIUS-brand power contactor in the Size S0 frame, 45 mm wide, and it mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. That 45 mm width is the panel footprint you need to leave — it's the same slot as other S0 contactors, so if you're swapping into an existing S0 rail, it drops in without shifting busbars. The coil terminals are screw-type, and the contactor carries an auxiliary switch built in.
Mounting and clearances — what the install needs
Mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward and backward. For side-by-side spacing, the spec calls for 10 mm upwards, 10 mm downwards, 10 mm forwards, and 6 mm at the side — that's the minimum clearance to adjacent devices for heat dissipation and arc containment. Operating temperature range is -25 to +60 °C, storage from -55 to +80 °C.
Switching duty and mechanical life
Rated for 1,000 operations per hour at AC-1, 750/h at AC-2 and AC-3, and 250/h at AC-4. The arcing time is 10 ms. Mechanical life is typical 10 million operations. The main contact wire range accepts solid or stranded 1 to 10 mm², and the auxiliary contacts take 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²).