What the 2 A AC-3 rating means for your motor load
The 3RK4340-3FR51-0BA0: The 2 A at AC-3 400 V rating is the motor-switching current — it governs the motor full-load current this starter can handle under the toughest switching duty (starting and plugging). For a 400 V three-phase induction motor, 2 A AC-3 corresponds to roughly 0.75 kW output. This is a direct starter (no reversing), so it's sized for a single-speed, one-direction motor — a pump, fan, or conveyor segment.
Enclosure and mounting for panel and field installation
IP55 protection means the housing is dust-protected and water-jet resistant — suitable for installation in a control cabinet with a gland plate or in a field enclosure where washdowns occur. Dimensions are 145 mm deep, 182 mm wide, 220 mm high — a compact footprint for a 3-pole motor starter with integrated overload.
Control supply and communication — what's built in and what's not
The control supply is 20.4 to 26.4 VDC — a standard 24 VDC nominal control voltage with a wide tolerance for brownout conditions. This unit has no bus communication (no PROFINET, PROFIBUS, or AS-Interface) and zero digital inputs onboard; it's an I/O-controlled starter that expects hardwired signals from a PLC or relay. If your design requires fieldbus connectivity, you'd step up to a SIRIUS 3RK4 variant with the communication module. For a simple hardwired motor group, this is the clean, cost-effective pick.