What this part is and where it fits
The Siemens 3RT1935-5AV01 is a SIRIUS magnet coil designed for Size S2 contactors, with a 400 V AC control supply voltage at 50 Hz. It uses a screw terminal connection for the coil wires. This coil is the replacement or spare part for the contactor's magnetic system — when the original coil fails or the voltage needs changing, this is the drop-in component that mounts onto the contactor's armature stack.
Lifecycle status and sourcing reality
The 3RT1935-5AV01 is a phased-out product. The manufacturer lists the successor as the SIRIUS 3RT2 series, meaning new designs or panel rebuilds should migrate to that platform. For existing panels that still carry this coil, replacement units are sourced through independent distribution channels. Availability and current pricing are confirmed at quote time against an RFQ.
What the ratings mean for fit
The 400 V AC rating at 50 Hz defines the control voltage that must be supplied to the coil terminals. If your panel runs a 400 V AC control transformer at 50 Hz, this coil engages the contactor's magnetic circuit directly. The operating range of 0.8... 1.1 times the rated voltage means the coil reliably picks up between 320 V and 440 V and holds in down to about 320 V — useful to know if your line voltage sags under load. The screw terminal connection accepts standard solid or stranded wire, making it straightforward to swap during a line-down event without special tooling.