What it is and what it does
The Siemens 3RT1955-5AP31-0ST0 is a withdrawable solenoid coil purpose-built for the 3RT105 contactor frame. It operates on 220-240 V AC (50-60 Hz) or DC supply, and includes a standard economy circuit that reduces holding power once the contactor is sealed. The screw terminal connection matches typical panel wiring practice. A 20 ms reduced break time means the coil drops out faster than the standard version — relevant when you need quicker contact separation for load disconnection or safety circuit response.
Integration notes
The withdrawable design means the coil unclips from the contactor magnet assembly without disturbing the main power wiring — useful for a panel OEM or field service swap. The screw terminals accept standard ferrule or solid conductors. The economy circuit reduces continuous DC draw once the contactor picks, so factor that into your 24 VDC control supply budget if you're running multiple coils. The 20 ms reduced break time is a deliberate feature: it shortens the arc extinction delay, which can matter on inductive load switching or when coordinating with upstream protection.