SIRIUS 3RA2 non-fused motor starter, 24 V coil
The Siemens 3RA2125-1JA24-0BB4 is a SIRIUS non-fused motor starter, a direct starter design in size S0. It ships as a pre-assembled unit combining a contactor and a thermal bimetallic overload relay, so it arrives ready to snap onto the DIN rail and wire into the motor branch circuit. The 24 V coil means this starter is intended for control circuits running at 24 VAC/DC — common in PLC-driven panels where the I/O and safety relays share a 24 V bus.
Motor power ratings across common line voltages
This starter covers a range of motor sizes depending on the supply voltage. At 400 V it is rated for 4,000 W; at 500 V it handles 5,500 W. The AC-3 switching voltage is rated up to 690 V maximum. The thermal overload is bimetallic and field-adjustable — it responds to the motor's actual current draw, not just the line voltage. The supplied contactor is a 3RT2024-1BB40, and the link module is 3RA2921-1BA00, so the assembly is a matched set from the factory.
Mounting and panel fit — size S0 footprint
The starter snaps onto a DIN rail or can be screw-mounted using the additional push-in lug. Mounting position is vertical. The envelope is 45 mm wide, 107 mm deep, and 193.1 mm tall — the S0 frame size is a common footprint in Siemens SIRIUS panels, so it fits alongside other S0 components like the 3RV2 circuit-breaker (size S00) that feeds it. Clearance requirements: 30 mm upwards, 10 mm forwards, 10 mm downwards, and 9 mm at the side. No clearance needed at the back. The operating temperature range is -20 to +60 °C, with storage from -50 to +80 °C.