SIMATIC motor starter with PROFINET — 0.4 A, 55 kA SCCR
The Siemens 3RK1308-0AA00-0CP0 is a SIMATIC-branded direct-on-line motor starter combining a contactor, overload relay, and fieldbus interface in a single 30 mm-wide housing that plugs into a BaseUnit on the DIN rail. Rated 0.4 A at both 40 °C and 50 °C ambient — the minimum load is 50 % of the smallest adjustable rated current, so it is sized for fractional-horsepower motors in conveyor, pump, or fan duty where the line current stays under half an amp.
Fieldbus and I/O — PROFINET and PROFIBUS DP, 4 input / 2 output bytes
Supports both PROFINET and PROFIBUS DP protocols, so it fits into Siemens S7-1500 or S7-1200 controller environments as well as legacy PROFIBUS networks without a gateway. The module maps 4 bytes of input data and 2 bytes of output data — the note '4 via 3DI/LC module' indicates four digital inputs are routed through the load circuit monitoring, giving the PLC direct feedback on the motor current and contactor state. ON-delay is fixed at 20 ms;.
Trip class and protection — adjustable CLASS OFF / 5 / 10, safe state open
Trip class is selectable between OFF (no overload protection), CLASS 5, and CLASS 10 — CLASS 10 is the standard for standard-duty motor starting where the acceleration time is under 10 seconds; CLASS 5 is for fast-starting loads like small pumps that reach speed in under 5 seconds. The safe state is 'load circuit open' — on a fault or loss of communication, the output contacts open and the motor coasts to a stop, which is the expected fail-safe behavior for a direct-on-line starter in a safety-related control system. Supply voltage range is 20.4 to 28.8 V, compatible with standard 24 VDC control rails; overvoltage category III means it can be connected directly to the panel's distribution bus without additional surge suppression.
Panel fit and environment — 30 mm wide, -25 to +60 °C, vibration 2g
Dimensions are 150 mm depth, 30 mm width, 142 mm height — the 30 mm width is the same as a single Siemens SIRIUS 3RT2 contactor, so it occupies one standard slot on the mounting rail and leaves room for adjacent modules in a dense panel layout. Vibration resistance is 15 mm amplitude at 6 Hz and 2g up to 500 Hz; shock resistance is 6g for 11 ms — this qualifies the starter for machine-mounted applications on conveyors, packaging lines, or compressor skids where the panel is subject to continuous vibration.
Sourcing and lifecycle — current production, quoted to order
The MTBF is 48 a (years), which is the reliability figure for the electronic assembly — for a critical-spare holding decision, this means the expected failure rate is roughly 2 % per year in continuous operation at rated conditions.