What this contactor is and where it fits
The Siemens 3RT7027-1AV00 is a SIRIUS S0-frame 3-pole contactor with screw-type terminals for main and control circuits. It is rated for AC-3 switching up to 690 V and carries a DC-13 rating of 0.3 A at 220 V for inductive DC loads. The 45 mm width and 91 mm depth fit standard 35 mm DIN rail per EN 50022, and side-by-side mounting is supported without derating — useful when packing multiple contactors into a row for a motor control centre. The IP20 rating on the front and on the terminals means the contactor is finger-safe when installed in an enclosure — no additional shrouding needed for routine panel access. Pollution degree 3 suits industrial environments with conductive dust or occasional condensation.
Key ratings and what they mean for selection
The AC-3 operational current is specified at three voltage points: 6 A at 230 V, 3 A at 400 V, and 1 A at 690 V. These are the motor-switching currents the contactor can handle under typical induction-motor starting conditions (make and break under load). For DC-13 duty (solenoid/brake loads), the rated current is 0.3 A at 220 V. The maximum switching rate is 800 operations per hour in AC-3 and 250 in AC-4 — the lower AC-4 limit reflects the harsher plugging/reversing duty. Coil consumption is 0.82 W during pick-up and 0.24 W holding — low enough to daisy-chain multiple contactors on a single 24 VDC supply without exceeding the power budget of a typical PLC output card. The control supply voltage type is AC, so verify the coil voltage variant before wiring. Surge voltage resistance is 6 kV (impulse withstand), which is standard for industrial control panels and meets the basic insulation coordination requirements of IEC 60947-1. The auxiliary contacts are rated for PLC-level signals (17 V, 5 mA), so they can be wired directly to a digital input without a separate interface relay.