What This Part Is and What It Does
The Siemens SIRIUS 3RT1934-5BM42 is a 220 V DC magnet coil intended for Size S2 contactors. It uses spring-loaded connection technology, so wiring lands without screw terminals — just strip, insert, release. This is the replacement coil if you have a Size S2 contactor body that needs a 220 V DC pull-in and hold.
Fit and Mechanical Integration
This coil is sized for the SIRIUS Size S2 contactor frame. If your panel was built around a Size S2 contactor body (e.g., 3RT10 or 3RT13 series), this coil snaps onto the magnet armature without tools. The spring-loaded terminals accept 0.5–2.5 mm² solid or ferruled stranded wire. Verify the control voltage bus: 220 V DC nominal, and the coil dropout threshold is typically around 0.8× rated — so below 176 V DC the contactor drops out. That matters if your DC supply is unregulated or shared with inductive loads.