What this SIMATIC DOL starter is and what it does
The Siemens SIMATIC 3RK1308-0AB00-0CP0 is a direct-on-line motor starter in the 3RK1 family, designed for switching and protecting single-speed induction motors up to 1 A at 40 °C ambient. It integrates a contactor, overload relay, and PROFINET/PROFIBUS DP communication into one 30 mm-wide module that plugs into a common BaseUnit — no point-to-point wiring for the power bus. The safe state is load circuit open, and the trip class is adjustable OFF / 5 / 10, so you can match the thermal curve to the motor start profile. It draws 4 bytes of input data and 2 bytes of output data over the fieldbus, which is enough for status, control, and diagnostic feedback without eating into your PLC I/O budget.
Key ratings and what they mean for fit
Rated 1 A at both 40 °C and 50 °C — that is the continuous current the starter can carry in a 40 °C panel without derating. If your motor FLA is 0.9 A, this is a clean fit; above 1 A you step up in the family. The minimum load is 50 % of the smallest adjustable rated current, so it will not nuisance-trip on a lightly loaded motor. Short-circuit current rating (SCCR) is 55 kA at both 400 V and 500 V — that means the starter, when paired with the correct upstream fuse or breaker, can safely interrupt a fault up to 55 kA without welding contacts or rupturing the housing. Overvoltage category III and pollution degree 2 confirm it is rated for fixed-installation industrial panels, not just clean-room electronics.
Communication and control
This starter supports PROFINET and PROFIBUS DP protocols. ON-delay is 20 ms, OFF-delay 35 to 50 ms. On-site operation is supported. Supply voltage is 20.4 to 28.8 V.
Mounting and environment
Width is 30 mm, depth 150 mm, height 142 mm — it fits a standard DIN-rail footprint but needs 50 mm clearance above and below for airflow and cable bend radius. Mounting can be vertical or horizontal, but horizontal requires derating per the manual. Ambient operating range is -25 to +60 °C with derating above 40 °C; storage and transport go from -40 to +70 °C. Shock resistance is 6 g for 11 ms, vibration 15 mm at 6 Hz and 2 g up to 500 Hz — typical for machine-mount near conveyors and small pumps, but not for high-vibration crushers or presses.
Lifecycle and sourcing reality
Lifecycle stage is current. MTBF is 48 years. The part is sourced to order through independent distribution; availability and pricing confirmed at quote time.