The Siemens 3RT1934-5BD42 is a SIRIUS-brand magnet coil designed for Size S2 contactors. It's a 42 V DC coil with spring-loaded connection technology — the kind of replaceable coil you swap when the control voltage changes or the old one lets go out here in the grease.
Lifecycle and Sourcing
This part is listed as a phased-out product. The official successor is the SIRIUS 3RT2 series — same Size S2 footprint, same spring-loaded connection, but the 3RT2 coil family. If you're filling a BOM line or keeping a spare on the shelf for an existing panel, the 3RT1934-5BD42 is still spec'd into active systems; we source it to order against an RFQ. Availability and current pricing get confirmed at quote time.
What It Fits and How It Wires
This coil snaps into a SIRIUS Size S2 contactor — the same frame that carries the 3RT1044 and similar power contactors. Spring-loaded terminals accept 0.2–2.5 mm² solid or ferruled stranded, same as the standard DIN-rail terminal blocks you're already running. The 42 V DC rating means it pulls in clean on a 48 V nominal bus with a drop-out below about 34 V; verify your control transformer tap before committing the line.
Why This Coil Matters on the Route
A magnet coil is the part that takes the hit — every time the contactor cycles, that coil takes the inrush and the heat. On a conveyor line or a pump panel that cycles a few hundred times an hour, having the right DC coil voltage (42 V here) keeps the contactor from chattering or dropping out early. The spring-loaded connection means you're not fighting screw terminals when you swap it in a tight enclosure; strip 8 mm, push it in, done.