What it is and what it does
The Siemens 3RT2038-1AD04 is a SIRIUS Size S2 power contactor — a three-pole, electrically held device with screw-type main and coil terminals, intended for switching motor loads in control panels. It carries no built-in auxiliary switch block, so if you need N.O./N.C. feedback for a PLC or status lamp, you add a separate auxiliary contactor block that snaps onto the front. Its headline rating is 65 A at 480 V in AC-3 duty, which is the standard motor-switching category per IEC 60947-4-1 — that means it can make and break a locked-rotor current of about 6× rated, so it handles starting a 65 A FLA motor without welding contacts. At 230 V it carries a 15 hp motor load. The AC-1 (resistive) rating is not stated here, but the AC-3 figure is the one that governs motor selection. The coil is 24 VDC, drawing 6 A at rated voltage. That's a high inrush for a DC coil — verify your 24 VDC supply can deliver the peak without droop, especially if you're driving multiple contactors from the same power supply. The coil holds at 24 VDC nominal; dropout voltage is not listed here, but typical SIRIUS DC coils drop out around 18 V.
Mounting and panel fit
Mounts by screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The Size S2 footprint is 55 mm wide, 114 mm tall, 174 mm deep. Clearance: 10 mm above and below, 10 mm forward, 6 mm to the side. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — useful when you're squeezing it into a tight gland-plate area. Wire range: accepts 2× (0.5–1.5 mm²) or 2× (0.75–2.5 mm²) solid or stranded. Screw terminals are standard — no spring-cage option on this variant.
Switching frequency and endurance
Mechanical endurance is 10 million operations typical. Maximum switching rates: 700 cycles/hour in AC-1, 500 in AC-3, 350 in AC-2, 150 in AC-4. For AC-3e (enhanced) it's also 500 cycles/hour. If your application cycles faster than these rates, you'll need to derate or move to a larger frame.