What this SIRIUS S2 contactor does on the line
The Siemens 3RT1034-1BW40 is a SIRIUS power contactor in the S2 frame size, built to switch three-phase motor loads in a control panel. Its 48 VDC coil pulls in at 0.8 × rated voltage and drops out with a 20–30 ms delay — fast enough for most emergency-stop circuits but not a safety-rated instant-off. Rated for 18.5 kW at 500 V and 10 kW at 690 V in AC-3 duty, it handles the common 400 V class motor range up to about 30 kW depending on the load profile. The screw-type main terminals accept stranded cable up to 2 × 25 mm², so it lands in the panel without lug adapters on moderate feeds. Mechanical life is rated at 10 million cycles typical, with maximum operating rates of 1 200 ops/h in AC-1 and 1 000 ops/h in AC-3. Arcing time sits at 10–15 ms.
Panel fit and wiring constraints
Mounts on 35 mm DIN rail per EN 50022, screw or snap-on. At 55 mm wide and 112 mm tall. Side-by-side mounting is allowed. Front face carries an IP20 rating; terminal area is IP00. Solid wire acceptance: 2 × (0.5–1.5 mm²), 2 × (0.75–2.5 mm²), max 2 × (0.75–4 mm²). Stranded: 2 × (0.75–25 mm²). For the control circuit, the 48 VDC coil terminals take the smaller solid range. Pollution degree 3 means it's rated for industrial environments with conductive pollution — no conformal-coating requirement for the contactor itself, but the panel environment should be dry.