The Siemens 3RT1035-3KJ84-0LA0 is a SIRIUS S2-frame power contactor rated for motor switching at 22 kW on 500 V AC-3 duty, and 18.5 kW at 400 V AC-2. In the heavier AC-4 category (plugging, inching) it handles 35 A at 400 V. The S2 frame is the middle size in the SIRIUS contactor family, sitting between the compact S0 and the larger S3. Main circuit connections are screw-type terminals. Wire ranges: solid 2x (0.25 to 2.5 mm²), stranded 2x (0.75 to 25 mm²), and a second stranded range 2x (0.75 to 16 mm²).
This is a panel-mount component — IP00 on the front and at the terminals, so it lives inside an enclosure, not out in the weather. Dimensions: 80 mm wide, 110 mm high, 167 mm deep. Switching frequencies: 1200 cycles/hour at AC-1 (resistive), 1000 at AC-3 (motor start), 600 at AC-2, and 300 at AC-4. The AC-4 limit is the binding constraint for high-duty reversing applications.
Control circuit and aux contacts
The coil is rated 72 V. Pickup and dropout timing: DC operate time 20 to 25 ms, arcing time 10 to 15 ms. The auxiliary contact block (integrated or add-on) carries 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, and 3 A at 400 V. The 24 V 10 A rating is the one to note for PLC output interfacing. Control supply threshold: initial value 0.7, full-scale value 1.25 — these are the pickup and dropout ratios relative to the rated control supply voltage. The contactor picks up at 70% of rated voltage and drops out at 125% (overvoltage release).