The Siemens 3RK1301-0BB20-0AA3 is a SIMATIC-branded motor starter — a direct-start unit rated for 3 kW at 400 V 50 Hz, with an adjustable trip class of CLASS 10 and 10A. That means it protects motor loads up to that power level against overload, and the trip class setting lets you match the thermal curve to the motor's starting profile: CLASS 10 for fast-starting loads like pumps and fans, 10A for slightly longer acceleration times on conveyors or compressors. It communicates over both PROFINET and PROFIBUS DP, so it fits into either a modern industrial Ethernet architecture or a legacy fieldbus backbone without a gateway. The unit has 2 bytes of input data and 2 bytes of output data — enough for status and control words on a single motor branch. Supply voltage is 24 V DC nominal, with a permissible range of 20.4 to 28.8 V DC. The main circuit and infeed use screw-type terminals — no spring-cage here, so factor in the extra wiring time if your panel shop is standardized on push-in connectors.
The starter mounts pluggable onto a terminal module — it's not a standalone DIN-rail brick. That means the base terminal block stays wired in the panel, and the electronics module clips on top. Handy for swap-outs: you can replace the control module without pulling the power wiring. Mounting position is vertical or horizontal, so you have some layout flexibility inside the enclosure. Dimensions are 290 mm high, 65 mm wide, and 150 mm deep. That's a tall, narrow footprint — it'll eat vertical space in the cabinet but leaves room alongside for other starters. Protection class is IP20, so it's for clean, dry indoor panels only — no washdown or dusty environments without a separate enclosure. Rated for operation from 0 to 60 °C ambient, storage and transport from -40 to +70 °C. Vibration resistance is 2g, shock resistance 5g at 11 ms. Pollution degree is 3 at 400 V and 2 at 500 V per IEC 60664 / IEC 61131 — that's typical for industrial control panels where some conductive dust or condensation is expected.