Integrator's Spec Recap
The Siemens SIRIUS 3RT1026-3BB44-3MA0 is a power contactor in the S0 frame size, designed for motor switching and general load management in control panels. It mounts via screw and snap-on onto a 35 mm DIN rail per EN 50022, occupying 45 mm width on the rail. Rated for 11 kW at 400 V in AC-2 duty (slip-ring motor starting), it handles 15.5 A in AC-4 (plugging/inching) at the same voltage. The AC-12 resistive load rating is 10 A, covering control circuit isolation needs. Coil is 24 VDC, drawing 5.4 W for both closing and holding — a fixed-gap DC magnet that doesn't hum. The front face carries IP20 protection; the terminal area is IP00, so live parts are exposed once wired.
Mounting and Wiring Constraints
Screw-type terminals on the main circuit accept 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), or a single 10 mm² conductor. Solid wire range is 2x (0.25 to 2.5 mm²). AWG equivalents: 2x (16 to 12), 2x (14 to 10), or 1x 8 for the main contacts. Side-by-side mounting is permitted with a 6 mm clearance at the side. The contactor stands 85 mm tall and 150 mm deep, so factor that into gland-plate clearance and enclosure depth. Operating temperature range is -25 to +60 °C, with pollution degree 3 (conductive or dry non-conductive pollution). Maximum operating altitude is 2,000 m without derating.
Short-Circuit Coordination and Lifecycle
For Type 2 coordination (no damage to the contactor), the required upstream fuse is gL/gG 35 A. For Type 1 coordination (contactor may need replacement), a 100 A gL/gG fuse is permitted. This matters when the contactor sits in a branch with high fault current — the fuse limits let-through energy to protect downstream loads. Mechanical life is rated at 10 million operations typical. The DC coil's holding power stays at 5.4 W, so no additional thermal load from a holding-economy resistor is needed.