What it is and where it lands
The Siemens 3RT7027-1AP00 is a SIRIUS 3-pole contactor in the S0 frame size, built for motor switching and general load control in industrial panels. It mounts on a 35 mm DIN rail per DIN EN 50022 using either screw fixing or snap-on — the fastening method is dual, so you can drop it into a new rail or bolt it to a backplate without adapters. Rated operational current at AC-3 peaks at 690 V maximum, and the auxiliary contacts are verified for PLC-level switching down to 17 V at 5 mA — meaning this contactor can drive a logic input directly without an interposing relay. The coil draws 0.82 W on closing and holds at 0.24 W DC, so the control transformer can be sized lean — a common pain point on multi-contactor panels.
Mounting and integration
Width is 45 mm, depth 91 mm, height 85.5 mm — fits the standard S0 footprint. Side-by-side mounting is allowed with no derating gap, which keeps row density high on the DIN rail. Mounting position is flexible: ±180° rotation on a vertical surface, and can be tilted forward or backward by ±22.5°. This matters when you're fitting into a tight enclosure or a swing frame. IP20 on the front and at the terminals — standard for enclosed panel gear, not for washdown zones. Pollution degree 3 means it's rated for conductive pollution typical in industrial atmospheres.
Switching duty and ratings
Three main poles, all normally open. The contactor is rated for AC-3 duty (squirrel-cage motor switching) up to 690 V, and carries a DC-13 rating of 0.3 A at 220 V for solenoid loads. Maximum switching frequency is 800 cycles per hour under AC-3, dropping to 250 cycles per hour under AC-4 (plugging/inching). For short-circuit protection, type 1 coordination calls for a 125 A gL/gG fuse; type 2 coordination requires a 50 A fuse. Surge voltage resistance is 6 kV, and the contactor withstands shock pulses of 12.5g at 5 ms and 7.8g at 10 ms — relevant for mobile or vibrating installations.