What it is and what the ratings mean for your panel
The Siemens 3RT2037-3NB30-Z W96 is a size S2 power contactor from the SIRIUS family, rated for AC-3e / AC-3 duty at 65 A and 30 kW at 400 V. That 65 A AC-3 rating is the motor-switching current — it handles the inrush and breaking of three-phase induction motors up to that load, not just resistive heating. The coil accepts 20-33 V AC/DC, 50/60 Hz, with an integrated varistor for suppression, so you can wire it directly to a 24 VDC control supply without adding an external snubber.
Termination and auxiliary contacts — wiring constraints
Main circuit uses screw terminals; the control circuit and auxiliary contacts use spring-loaded terminals. That mix matters for panel assembly: power wiring gets the torque-able screw clamp, while the coil and aux wiring snap in without a screwdriver — speeds up control-wiring termination on a DIN-rail panel. The built-in auxiliary contacts are 1 NO + 1 NC, enough for a feedback loop or a status light without adding a side-mount block.
Compliance and documentation
RoHS compliant since October 2014, with a REACH Article 33 notification for lead (CAS 7439-92-1) above 0.1% w/w. Export control is AL: N / ECCN: N — no special license needed for standard industrial use.