Panel fit and coil details
The Siemens 3RT2038-3XF40-0LA2 is a SIRIUS size S2 power contactor with a 110 V DC coil terminated through spring-type terminals. It screws or snaps onto 35 mm DIN rail per DIN EN 60715, so it integrates into a standard panel enclosure without adapters. The DC coil pulls 1.5 A inrush and picks up at 70% of rated voltage; dropout is at 125% of rated, with a dropout time of 30 to 55 ms. That dropout window matters for sequencing logic — if your control scheme relies on a fast drop, the 30 ms floor is the number to design around.
Ratings and what they mean for the load
Rated 65 A at 480 V and 62 A at 600 V — those are the AC-3 motor-switching figures that govern real motor loads. The 65 A at 480 V means it can handle a 50 hp motor at 480 V three-phase; the 62 A at 600 V covers a 60 hp motor at that voltage. For resistive loads (AC-1), the contactor carries higher current, but the motor-duty number is the one that decides fit for pump, fan, or compressor duty. The main contact configuration is listed as 18 to 1 — that's 3 normally open power poles plus 1 normally open auxiliary, with a separate auxiliary switch block included. Mechanical life is 10 million cycles typical, so it's built for high-cycle applications like conveyor lines or packaging machines.
Mounting and clearance
Dimensions: 114 mm high, 55 mm wide, 130 mm deep. The 55 mm width is the DIN-rail footprint — it occupies three 18 mm module spaces, which is standard for a size S2 contactor. Clearance requirements: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side. That 6 mm side clearance is tighter than the vertical clearances, so when packing multiple contactors side-by-side on the rail, the 6 mm gap is the limiting dimension. Mounting position is flexible: +/-180° rotation on a vertical surface, and can be tilted forward/backward by +/-22.5°. That helps when the panel layout forces an odd orientation. Wire size: 2 x 0.5 to 2.5 mm² solid or stranded — spring terminals, so no screw torque to verify, but strip length must be consistent.
Switching performance and auxiliary ratings
Arcing time is 10 to 20 ms — that's the duration the arc sustains between main contacts during interruption. For DC switching, the arc extinguishes faster than AC because of the natural current zero, but the 10-20 ms window is normal for a DC coil contactor at these power levels. Maximum switching frequency in AC-4 duty (plugging/reversing) is 150 operations per hour — that's the limit for severe switching, not continuous running. For the auxiliary contacts, rated currents at various DC voltages: 10 A at 24 V, 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, 0.6 A at 440 V, 2 A at 500 V. The 10 A at 24 V is the highest auxiliary rating — useful for pilot-duty control circuits at low voltage.