What It Is and Where It Goes
The Siemens 3RT2027-2NB30-ZX95 is a SIRIUS S0-frame power contactor — the workhorse for switching motor loads and resistive heaters inside a control panel. It mounts on 35 mm DIN rail per DIN EN 60715, either screwed or snapped on, and the mounting position allows ±180° rotation on a vertical surface plus ±22.5° tilt forward or backward, which helps when you're fitting it into a crowded enclosure and the rail isn't perfectly level.
Key Ratings and What They Mean for the Buyer
The contactor is rated for AC-3 motor switching up to 750 operations per hour, and AC-4 (plugging/reversing) at 250 ops/h. That 750 ops/h ceiling on AC-3 means it handles frequent starts on a conveyor or pump without overheating the contacts — it's not a continuous-duty relay, it's built for cyclic loads. The spring-type terminals accept solid or stranded wire from 1 to 10 mm², and the auxiliary switch is included, so you don't need to order a separate side-mount block for basic feedback. Inrush current peaks at 3 A, which matters when you're sizing the control transformer or the DC supply for the coil — that's the momentary draw when the magnet pulls in. The coil itself is rated 21–28 V, so a standard 24 VDC supply is fine, but watch the drop-out threshold: below about 18 V it releases, which is typical for this class.
Panel Fit and Dimensions
The S0 frame is 45 mm wide, 102 mm tall, and 107 mm deep. That depth is the dimension from the DIN rail mounting surface to the front of the terminals — important when you're calculating door clearance or gland-plate depth. Side clearance is 6 mm, and vertical spacing (up/down/forward) is 10 mm. Solid or stranded wire from 1 to 10 mm² fits the spring terminals; for finer control wiring, 2x 0.5–2.5 mm² is allowed.