What It Is and Where It Fits
The Siemens SIRIUS 3RT1934-5BP42 is a replacement magnet coil for Size S2 contactors in the SIRIUS family. It uses spring-loaded connection technology and is rated for 230 V DC control supply voltage. This coil is the drop-in service part for an existing S2 contactor frame — you swap the coil, not the whole contactor.
Lifecycle and Sourcing Reality
This part is flagged as a phased-out product. The official successor is the SIRIUS 3RT2 series. If you're holding a BOM line with 3RT1934-5BP42, the coil is still available through independent channels — quoted to order against an RFQ — but the clock is running on factory support. For new designs or a panel respin, the 3RT2 series is the path forward.
What the DC Coil Rating Means
The 230 V DC coil is a continuous-duty solenoid. Unlike an AC coil, a DC coil does not have an inrush current spike — it draws steady holding current once sealed. That makes it easier on the control transformer and PLC output card driving it, but it also means the supply must hold steady at 230 V DC; a sag below the dropout threshold releases the contactor.