The Siemens 3RT1935-5AG21 is a SIRIUS-brand magnet coil designed to power the electromagnetic actuator on Size S2 contactors. It's the replacement coil you'd pull when the original burns out or the control voltage changes — not a standalone contactor, just the coil assembly. The coil draws a holding power in the range of 0.8 to 1.1 VA at 50 Hz — that's the steady-state power it pulls once the contactor is sealed in.
This is a phased-out product per Siemens. The official successor is the SIRIUS 3RT2 series coil. If you're maintaining a panel that was originally built with this part, you'll want to quote the 3RT1935-5AG21 against an RFQ — we source it through independent distribution channels.
Deployment context
The screw terminal connections match the standard panel wiring practice — spring-cage or screw-clamp depending on the contactor variant. Out here in the grease, if you're swapping a coil on a conveyor starter, make sure the panel power is locked out before you pull the old one; the coil terminals are live whenever the control transformer is hot.