Contactor ratings and what they mean for your panel
The Siemens 3RT2037-3XJ44-0LA2 is a SIRIUS-branded contactor in size S2, rated 65 A at 480 V and 52 A at 600 V — those are the thermal current values that govern continuous motor-load switching in AC-3 duty. The 65 A at 480 V figure means this contactor handles a 65 A motor load at that voltage without exceeding temperature rise limits; the 52 A at 600 V derates slightly due to higher voltage stress on the arc chamber. For a 480 V three-phase motor, that 65 A rating typically covers a 50 hp motor, though exact sizing depends on the motor FLA and service factor. The contactor carries a 10 hp rating at 230 V, confirming its intended use for larger industrial loads, not fractional-horsepower machines. Mounting is straightforward: screw and snap-on onto 35 mm standard mounting rail per DIN EN 60715. The mounting position allows +/-180° rotation on a vertical surface and can be tilted forward/backward by +/-22.5°, so panel layout flexibility is good. Clearance requirements are specified: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the side — these are minimum air gaps for arc venting and heat dissipation. The 178 mm depth, 55 mm width, and 114 mm height mean it fits standard S2 contactor footprints; verify your enclosure depth clears the 178 mm with wiring space.
Coil and auxiliary details
The coil is DC-operated with spring-type terminals. Rated coil voltage is 72 V DC, with an extended operating range design (0.7 to 1.25 times rated value). The DC coil draws 6 A at 24 V rated value, 2 A at 48 V, 2 A at 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V — these are the coil inrush/holding currents at various DC control voltages. For a 72 V DC coil, the actual draw will fall between the 60 V and 110 V curves; expect roughly 1.5 A inrush. The spring-type terminals accept 2x (0.5 to 2.5 mm²) solid or stranded wire — use ferrules on stranded for reliable termination.