S0-frame power contactor for motor and resistive loads
The Siemens 3RT1026-1AP00-0BA0 is a SIRIUS power contactor in the S0 frame size, with three normally-open main contacts rated for AC-4 switching at 15.5 A at 400 V — the duty cycle for plugging and inching motor loads, not just steady-state running. The 45 mm width and 85 mm height (91 mm depth) fit the standard 35 mm DIN rail per EN 50022, with screw-and-snap-on mounting that locks into place without tools. Main circuit terminals accept solid or stranded conductors: 2x (0.5–1.5 mm²), 2x (0.75–2.5 mm²), up to 2x (0.75–4 mm²) for the control circuit, and 2x (1–2.5 mm²), 2x (2.5–6 mm²), up to 2x 10 mm² for the main circuit — covering most panel wiring from signal-level to motor feed. Auxiliary and control circuits also use screw-type terminals, consistent with the main circuit termination. The contactor carries IP20 on the front face (finger-safe when panel-mounted) and IP00 at the terminals — standard for open-panel installation where the enclosure provides the overall ingress protection. Side-by-side mounting is permitted, so you can gang multiple units without spacing gaps.
Coordination and protection
For type 1 coordination (no weld prevention, but the contactor remains operable after a short circuit), the required upstream fuse is gL/gG 100 A. For type 2 coordination (no damage to the contactor), the fuse drops to gL/gG 35 A. That difference matters when you're specifying a motor starter package — the 35 A limit gives you a smaller fuse and better selectivity downstream, but the 100 A rating tells you the contactor can survive a fault without welding if the coordination class allows it. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive due to condensation) is the rating — typical for industrial control panels not in a sealed, climate-controlled environment. The operating temperature range of -25 °C to +60 °C covers most plant-floor conditions, including unheated warehouses in winter.