The Siemens 3RT1346-1BB40 is a SIRIUS S3 power contactor rated for 53 kW at 230 V at 60 °C, with a 24 VDC coil drawing 15 W closing power. The screw-type terminals on both main and auxiliary circuits accept up to 50 mm² stranded (2x 10–50 mm²) or 2x 4 mm² solid, so it handles the heavier power feeds without needing a separate terminal block.
Mounts via screw or snap-on onto 35 mm or 75 mm standard DIN rail — the S3 frame (146 x 93 x 152 mm) fits most panel layouts, and side-by-side mounting is allowed with no derating gap. The IP20 front enclosure keeps fingers off live terminals inside the panel; the terminal area itself is IP00, so it expects enclosure protection.
Ratings in context
The 24 VDC coil picks up at 0.8 x rated (19.2 V) and drops out at 1.1 x rated (26.4 V), with a closing time of 14–20 ms and arcing time of 10–15 ms — fast enough for most motor-starting sequences. The auxiliary contact ratings cover the common control voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, so it can drive small contactors or PLC inputs directly. Insulation voltage is rated 1 000 V, giving headroom for 690 V systems. For short-circuit protection, the spec calls for a 160 A gL/gG fuse with type 2 coordination — that's the fuse size to order if you're building a coordinated starter.