What this contactor is and where it fits
The Siemens 3RT2337-3NB30 is a 4-pole SIRIUS 3RT.3 contactor rated 110 A in AC-1 duty at 400 V and 40 °C ambient — that resistive-heating rating is the one that governs continuous current in heater banks, lighting panels, or distribution loads where inrush is low. The coil pulls in on 20-33 V AC/DC, 50/60 Hz, with a built-in varistor for suppression; you don't need an external snubber across the coil terminals. Main circuit lands on screw terminals, while the auxiliary (1 NO + 1 NC) and control wiring use spring-loaded terminals — a mixed termination scheme that saves time on the control wiring side while keeping power connections under a screw clamp.
Terminal layout and panel integration
Size S2 footprint — the packaging dimensions are 122.5 x 82 x 142 mm, so it occupies a standard contactor slot on the DIN rail. The mixed termination matters at the panel gland plate: power wires (main circuit) land on screw clamps, which accept larger cable cross-sections typical for 110 A; the auxiliary and control circuit land on spring-loaded terminals, which are faster to wire and less prone to loosening under vibration. Keep the control wiring to the spring terminals and the load wiring to the screw terminals — that's the intended split.
Compliance and documentation
RoHS compliant since October 2014. REACH Article 33 disclosure: the part contains lead (CAS 7439-92-1) above 0.1% w/w in one or more homogeneous materials — standard for contactor silver-alloy contacts. Export control is AL N / ECCN N, so no special licensing for cross-border shipment. Group code R711, product group 5338 — these are Siemens internal classification codes used for catalog filtering and cross-reference lookups.