What it is and what it does
The Siemens 3RK1300-1ES01-0AA1 is an EM 300 DS electromechanical direct starter designed for the ET 200X distributed I/O system. It integrates motor starting, bimetal overload protection, and PROFIBUS DP communication into a single IP65-rated enclosure that mounts directly on the machine or conveyor section, eliminating a separate control panel for small motor groups. Rated for AC-3 duty at 1.5 kW on a 400 V supply, the starter handles the inductive load of standard three-phase squirrel-cage motors up to that power. The setting range of 2.8 to 4.0 A means the bimetal overload relay is field-adjustable to match the motor nameplate FLA within that window — critical for protecting the motor without nuisance tripping. The built-in brake contact (rated DC 24 V / 3 A) controls an externally supplied motor brake, so a single device handles both motor power and brake release. This saves a separate relay and simplifies wiring in applications like vertical conveyors or palletizers where the brake must release before the motor starts.
Key ratings and what they mean for fit
The AC-3 rating of 1.5 kW at 400 V is the motor-switching capability — it defines the largest standard induction motor this starter can handle under full-load starting conditions. The 50 A short-circuit breaking capacity (Icu) at 400 V means the integrated short-circuit protection (designed for use with upstream circuit-breakers) can safely interrupt a fault up to that level without welding contacts or cascading damage upstream. Operating voltage of 400 to 500 V AC covers the common European 400 V three-phase networks and 480 V North American systems. The DC 24 V control voltage is standard for industrial control circuits, so the starter can be driven directly by a PLC output or a 24 V relay without an intermediate converter. IP65 protection means the enclosure is dust-tight and protected against low-pressure water jets — suitable for washdown areas, outdoor installation under cover, or dusty environments like sawmills or grain handling. The 0 to 55 °C operating range covers most factory-floor conditions without derating.
Mounting and connectivity
The 3RK1300-1ES01-0AA1 measures 140 mm wide, 270 mm high, and 134 mm deep, matching the ET 200X modular footprint. It connects to the motor and power supply via tab terminals on the main current circuit, while the 9-pole motor feeder and 9-pole power connection cables plug into the device — no hardwiring inside the enclosure. PROFIBUS DP communication is integrated, so the starter reports status and accepts start/stop commands directly over the fieldbus without a separate I/O module. The electromechanical switching contacts provide galvanic isolation between the control circuit and the motor circuit — important for safety and noise immunity.
Sourcing and lifecycle
For a BOM line that calls out this exact order code, the fit is confirmed by the AC-3 power rating, the setting range, and the brake contact. If your application requires a different setting range or no brake output, Siemens offers other EM 300 DS variants in the same mechanical footprint.