What it is and what it does
The Siemens 3RT1026-1BP44 is a SIRIUS power contactor in the S0 frame size, designed for switching motor loads in industrial control panels. It mounts via screw and snap-on onto a 35 mm DIN rail per DIN EN 50022, so it integrates directly into a standard panel layout without adapters. Its key motor-switching ratings are 11 kW at 400 V in AC-2 duty (for slip-ring motors or reversing starts) and 15.5 A at 400 V in AC-4 duty (for plugging or inching). The AC-4 figure is the one that governs heavy jogging applications — that 15.5 A is the current the contacts can interrupt repeatedly during reversing or inching cycles. The main circuit uses screw-type terminals, accepting 2x (1... 2.5 mm²) or 2x (2.5... 6 mm²) or max. 2x 10 mm² stranded, and 2x (16... 12), 2x (14... 10), or 1x 8 AWG. The auxiliary contacts are rated for switching at various control voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V DC.
Sourcing and lifecycle
For BOM freeze or long-term planning, this part is stable: no PCN or EOL notice is known. If you need a second-source or drop-in replacement, the closest functional peer is the 3RT1023-1AL20 — same S0 frame, same screw-type main terminals, same DIN rail footprint — but its motor ratings differ (lower AC-3 current), so verify the load before swapping. The 3RT1026-1BP44 carries a higher AC-2/AC-4 capability, so it is the more robust choice for reversing or inching duty.
Integration and environment
The contactor occupies a 45 mm wide by 85 mm high by 150 mm deep footprint on the DIN rail. Side-by-side mounting is allowed (6 mm spacing at the side), so you can gang multiple units without derating — useful for multi-motor groups in a compact panel. Front protection is IP20, meaning it's touch-safe for the operator side but not sealed against washdown. The terminals themselves are rated IP00, so the wiring area is open — standard for panel-mount contactors where the enclosure provides the overall IP rating. Operating temperature range is -25 to +60 °C, and it's rated for pollution degree 3 (conductive pollution typical in industrial environments). Coil power is 5.4 W both for closing and holding at DC, so the control transformer sizing is straightforward — no inrush spike beyond the steady-state draw. For short-circuit coordination, type 2 coordination requires a 35 A gL/gG fuse; type 1 allows up to 100 A gL/gG.