What This SIRIUS S2 Contactor Does in Your Panel
The 3RT2337-1AC20 is a SIRIUS S2 contactor from Siemens — current production, active line. It's built to switch motor loads in control panels, and the S2 frame size tells you it's the middle-duty chassis in the SIRIUS family, good for a range of industrial motor applications up to its rated thermal current. That's handy when you're squeezing this into a crowded backpanel and the rail isn't perfectly level. Clearance distances are tight — 10 mm up, down, and forward, 6 mm to the side — so you can pack these side-by-side in a row without leaving a gap the size of your fist. The depth is 130 mm, width 75 mm, height 114 mm, which is a standard S2 footprint.
Ratings That Matter on the Line
Out here in the grease, a contactor that sees one cycle per minute on a conveyor line will run nearly 20 years before the mechanicals wear out. The main contact rating is listed as 18 to 1. The auxiliary switch is included, with contact ratings: 10 A at 24 V AC, 10 A at 230 V, 3 A at 400 V, 1 A at 690 V.
Wiring and Integration
Terminals accept solid or stranded wire: 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²). That's standard for control wiring — you can land two 1.5 mm² conductors per terminal for daisy-chaining or paralleling auxiliary circuits. Power consumption is 0.36 A at 50 Hz and 0.39 A at 60 Hz — about 9 VA on a 24 VAC transformer. That's low enough that a standard 50 VA control transformer can drive several of these plus a PLC and some relays. Up to two auxiliary switches can be attached (the unit ships with one included). If your circuit needs extra N/O or N/C contacts for feedback or interlocks, you can snap on a second without rewiring the main coil.