The Siemens 3RA2712-1AA00 is a SIRIUS AS-i function module that snaps onto the front of a communication-capable contactor (3RT20…-…..-0CC0) to give it AS-interface bus control for a direct starter. It mates with contactor sizes S00, S0, S2, and S3, which covers the common motor ranges up to around 37 kW depending on the contactor frame.
Control supply is 24 VDC only — no AC coil option. The module's varistor surge suppressor is designed for DC coils, so verify polarity if you're replacing a panel that had an AC-suppressed contactor. The screw terminals accept 0.5 to 4 mm² solid or 2x 0.5 to 2.5 mm² stranded, and with core-end processing 1x 0.5 to 2.5 mm² or 2x 0.5 to 1.5 mm². That covers most control-circuit wiring in industrial panels. AWG equivalents are 2x 20 to 14 for auxiliary contacts. Insulation voltage is rated 690 V AC at pollution degree 3, which is the standard industrial environment (conductive dust, occasional condensation). The module is EMC immune per IEC 60947-1 for industrial zones (ambience A) and emits within CISPR 11 limits for the same environment. Shock resistance is 11 g for 15 ms, vibration resistance 10–55 Hz at 0.35 mm. Mounting position is any orientation.
The module plugs directly onto the front of the contactor — no DIN-rail space taken beyond the contactor itself. The removable terminal block for auxiliary and control circuits means you can pre-wire the module before snapping it on, which saves time on repetitive panel builds. AS-interface bus communication is built in. The module acts as an AS-i slave, so the PLC sees the starter as a bus node. No separate I/O block needed for the start command or feedback.