What it is and where it fits
The Siemens 3RT7037-1AQ00 is a 3-pole S2-size contactor with an AC coil, screw-type terminals on both main and auxiliary circuits, and a rated insulation voltage of 690 V. It snaps onto a 35 mm DIN rail per EN 50022 or screws directly to a mounting plate — the fastening method gives you both options. The IP20 front enclosure protects against finger contact inside a panel; the terminal area is IP00, so it expects enclosure protection for the wiring zone. Pollution degree 3 rating means it handles conductive dust and condensation typical of industrial control cabinets without derating creepage distances.
What the ratings mean for your circuit
The AC-3 rated operational current maximum is 690 V — that's the voltage ceiling for switching squirrel-cage motors. The auxiliary contacts are rated for PLC-level reliability at 17 V, 5 mA, so they'll pick up a 24 VDC PLC input without contact oxidation issues. For DC-13 loads at 220 V, the contactor switches 0.3 A — useful for solenoid valves or DC brake coils in mixed-voltage panels. The closing power of the magnet coil draws 0.79 W DC; holding power drops to 0.36 W DC, meaning the coil runs cool once sealed and the control transformer can be sized lean. Switching frequency maxes at 800 operations per hour under AC-3 and 250 per hour under AC-4 — the AC-4 figure governs plugging and inching duty, so if your application reverses or jogs the motor frequently, stay under that ceiling.
Mounting and wiring constraints
The contactor accepts 2 x 0.5 to 1.5 mm² solid or stranded, or 2 x 0.75 to 2.5 mm² — fine for control wiring up to the main circuit rating. Side-by-side mounting is permitted, so you can gang multiple contactors on the same DIN rail without derating, provided the ambient stays within -10 to +55 °C during operation. Storage range is -25 to +70 °C. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward or backward — useful when the panel layout forces an angled subplate. Shock resistance is 15 g for 5 ms and 8 g for 10 ms sine pulse, which covers most industrial vibration environments short of a press or crusher.