What it is and where it fits
The Siemens SIRIUS 3RT1015-1KB42-ZW97 is a power contactor in the Size S00 frame, rated for 4 kW motor switching at 690 V AC-3 duty. The 24 V DC coil draws 2.3 W for both closing and holding, so the control transformer can be sized for continuous rather than inrush load. Mechanical life is typical 30 million operations. The built-in varistor suppresses coil transients — no external snubber needed on the control side. Mounts on 35 mm DIN rail per EN 50022, screw or snap-on. At 45 mm wide and 57.5 mm tall. Side-by-side mounting is permitted. Pollution degree 3 and IP20 on front and terminals.
Key ratings — what they mean for the buyer
AC-3 rating of 4 kW at 690 V is the headline motor-switching number — it covers 400 V three-phase motors up to about 3.5 kW. AC-4 at 400 V is 6.5 A, which governs reversing or plug-stop duty where the contactor breaks stalled-rotor current. AC-2 at 400 V is 3 kW for slip-ring motor switching. For resistive loads (AC-12), the main contacts carry 10 A continuous. The auxiliary contact is rated 10 A at 24 V, 6 A at 230 V, and 2 A at 60 V — enough for PLC inputs or small relay coils downstream. Short-circuit coordination: Type 2 requires a 20 A gL/gG fuse upstream; Type 1 allows 35 A. The screw terminals accept solid conductors from 0.5 to 4 mm² (2 x 0.75... 4 mm² max), or AWG 12 single. Operating temperature range -25 to +60 °C, with no derating stated for the upper end — but side-by-side mounting at full load in a 50 °C cabinet warrants a check on the thermal curve. Maximum altitude 2 000 m, no derating required below that.
Panel integration — what the installer needs
Depth is 72 mm from DIN rail front to furthest projection. Screw terminals accept solid conductors 0.5 to 1.5 mm² for control, up to 4 mm² for mains. Varistor is internal.