The Siemens 3RT1944-5BD41 is a SIRIUS-branded magnet coil for Size S3 contactors, terminated with screw terminals and wound for a 42 V DC control supply. It is the replacement coil for any 3RT1 S3 contactor body that needs a 42 V DC pull-in and hold coil.
What the 42 V DC rating means in practice
The 42 V DC coil voltage is a control-circuit spec, not a power rating. It means the coil is designed to pull in and hold reliably when supplied with 42 V DC — common in safety-isolated control circuits or legacy 48 V battery-backed systems stepped down slightly. On a Size S3 contactor, the coil draws its rated inrush then settles to a holding power; the screw terminals accept the same wire gauges as the main contactor terminals, typically 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²) for the control wiring. Mounts directly onto the 3RT1 S3 contactor body via the standard snap-on interface — no adapter needed.
Because the coil is a direct snap-on replacement for the S3 contactor, the DIN-rail footprint and panel cutout are already set by the contactor body. The screw terminals face forward, so wiring access is straightforward even in a dense enclosure. No additional clearance beyond the contactor's own side spacing (6 mm to grounded parts) is required for the coil itself.