The 3RT7027-1AF05 is a size S0 contactor from the Siemens SIRIUS family, rated for AC-3 and AC-3e duty up to 690 V maximum. The 3 NO main contacts handle motor switching in the S0 frame, which is the standard footprint for 15–30 A motor loads in European panel builds. The AC-3 maximum switching rate of 800 operations per hour sets the thermal cycling limit for repetitive starting; the AC-4 rate of 250/h applies when plugging or inching is part of the duty cycle — exceed that and the contactor will overheat before the overload relay trips. Screw-type terminals on both main and control circuits mean this is the version for panel shops that prefer screw clamps over spring-cage; the terminal accepts 2x (0.5…1.5 mm²) solid or 2x (0.75…2.5 mm²) stranded, so it covers the common motor control wiring sizes without adapters. The auxiliary contact reliability is specified for PLC-level control (17 V, 5 mA), meaning the silver-alloy contacts are designed to switch dry logic signals without needing a separate interface relay. That saves a DIN-rail slot in panels where the PLC output directly commands the contactor coil.
Side-by-side mounting is permitted with no derating gap, which is the usual SIRIUS S0 arrangement for multi-contactor motor starter groups. The product extension for auxiliary switches is supported, so a side-mount auxiliary contact block can be added later without replacing the contactor. That is useful when a BOM revision adds a feedback signal to the PLC after the initial build.
Fuse coordination is specified for both type 1 and type 2.