What this reversing starter is and what it does
The SIMATIC 3RK1301-1CB00-1AA2 is a reversing motor starter — a single device that handles forward and reverse direction control for a three-phase motor, with integrated overload protection. It's built as a reversing starter, meaning it contains two contactors mechanically interlocked so only one can close at a time, preventing a phase-to-phase short when reversing direction. The overload relay is set to Trip Class 10, which means it will trip within 10 seconds at 7.2× the thermal setting — appropriate for standard induction motors driving pumps, fans, or conveyors where the rotor doesn't lock for long. It's designed to plug onto a terminal module, so the power wiring stays in the panel while the control module can be swapped without disturbing the main circuit. The unit measures 265 mm high by 90 mm wide by 120 mm deep, which fits a standard 90 mm DIN-rail footprint. It's rated for vertical or horizontal mounting, giving flexibility in cabinet layout. The operating temperature range is 0 to 60 °C, so it's fine inside a ventilated enclosure but not for direct outdoor exposure.
Key ratings and what they mean for fit
The short-circuit breaking capacity is 50 kA at 400 V. That's the maximum fault current the device can safely interrupt without welding contacts or exploding. For a panel builder, this sets the SCCR (short-circuit current rating) of the branch circuit — you need upstream protection (fuse or breaker) rated to limit let-through to 50 kA or less. This is a strong rating, suitable for industrial mains with high fault capacity. Supply voltage is 24 V DC nominal, with a permissible range of 20.4 to 28.8 V. The coil holds reliably at 24 V; if your control supply dips below 20.4 V during a brownout, the starter drops out. The maximum operating frequency is 750 cycles per hour — that's about one start every 4.8 seconds, which covers most reversing duty cycles but not high-speed jogging. The unit supports PROFINET and PROFIBUS DP protocols, so it can be integrated into a Siemens S7 automation network directly. The I/O assignment is 1 byte each for inputs and outputs, which maps to a small data block in the PLC for control and status. There are no onboard digital I/O points — all control signals come over the fieldbus.
Lifecycle and sourcing reality
The product brand is SIMATIC, which is Siemens' automation platform. The pollution degree rating is 3 at 400 V and 2 at 500 V per IEC 60664 / IEC 61131 — this means it's suitable for industrial environments with conductive dust or occasional condensation, but not for wet or corrosive atmospheres without additional enclosure protection.