What It Is and What It Does
The Siemens 3RT1955-5AS31-0ST0 is a withdrawable drive solenoid coil designed specifically for the 3RT105 series of contactors. It operates on 500-550 V AC (50...60 Hz) or DC supply, using a screw terminal connection. The coil includes an economy circuit to reduce holding power and features a reduced break time of 20 ms, which means the contactor opens faster than standard — useful in applications where arc extinction or rapid load disconnect matters.
Integration Note
This is a withdrawable drive — it slides into the 3RT105 contactor base without disturbing the power wiring. The screw terminals accept the coil supply; the economy circuit inside the coil module handles the transition from pick-up to hold voltage. The 20 ms reduced break time is a mechanical spec, not electrical — it shortens the drop-out delay, which can help with coordination in fast-switching circuits.