The Siemens 3RT1034-3BB40-ZX95 is a SIRIUS S2 power contactor, rated for switching motor loads up to 15 kW in AC-2 duty at 400 V, and handling 29 A in AC-4 at 400 V for high-stress reversing or inching applications. The S2 frame size (55 mm wide, 112 mm tall, 130 mm deep) fits standard cabinet layouts without crowding adjacent devices.
The AC-2 rating of 15 kW at 400 V means this contactor is sized for slip-ring motor starting and stopping — the kind of moderate-duty cycle found on crane hoists or conveyor drives. The AC-4 rating of 29 A at 400 V covers plugging and inching, where the contactor must interrupt locked-rotor current. For resistive loads (AC-1), the switching rate peaks at 1,200 operations per hour, so it can handle fast cycling in heating or lighting banks. The 24 VDC coil holds reliably at 24 V nominal.