What this reversing starter does
The Siemens 3RK1323-5BS41-1AA0 is an ECOFAST reversing starter — a compact, IP65-rated unit that combines a reversing contactor pair with solid-state electronic overload protection, all in one enclosure. It switches motor loads up to 1.1 kW at AC-3 duty on a 400 V supply, with the current adjustable from 0.3 A to 3.0 A. The solid-state overload provides accurate, drift-free protection against motor heating, unlike a bimetal relay that can shift over time. The mechanical switching contacts handle the power circuit, while the AS-Interface bus connection carries control and diagnostics — no parallel control wiring needed.
The 1.1 kW at AC-3 400 V rating tells you the motor power this starter can handle in the most common industrial duty — starting and stopping a squirrel-cage induction motor under load. The 0.3 A to 3.0 A adjustment range covers small motors, typically fractional to about 3 HP at 400 V three-phase. The operating temperature range of -20 to +40 °C is standard for indoor industrial environments; if your line runs hotter than 40 °C, the overload must be derated per the thermal curve. The main circuit connects via tab terminals, not screw clamps — so your panel wiring plan needs the matching tab receptacles, typically 6.3 mm or 4.8 mm fastons.
Integration with AS-Interface
The AS-Interface protocol connection carries both the reversing commands (forward/reverse) and the overload trip signal back to the controller. Two digital inputs at 24 V DC are integrated for local pushbuttons or limit switches. The enclosure is plastic, IP65, sized at 130 mm wide, 250 mm high, 91 mm deep — it mounts directly on the machine frame via the ECOFAST base plate, not on a DIN rail. No separate contactor panel is needed. The bus communication function is built in; no external gateway module is required for AS-Interface.