What it is and what it does
The Siemens 3RT1026-3BB48-0PA7 is a SIRIUS power contactor in the S0 frame size, built for switching motor loads in industrial control panels. It carries an AC-2 rating of 11 kW at 400 V for slip-ring motors and an AC-4 rating of 15.5 A at 400 V for reversing or inching duty — the AC-4 figure governs the real thermal stress during plugging or jogging cycles, not the steady-state AC-1 number. The magnet coil pulls 5.4 W on pickup and holds at the same 5.4 W DC, so there is no power-drop after closing — verify your 24 VDC supply can sustain that continuous draw across all contactors in the panel.
Mounting and panel integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022. The S0 footprint measures 65 mm wide by 85 mm tall by 101 mm deep — the 101 mm depth is the dimension that matters for enclosure depth clearance, especially if a gland plate or door-mounted device sits behind the contactor. Side-by-side mounting is permitted, so you can gang multiple units without vertical spacing, but watch the heat buildup: the IP20 front enclosure keeps fingers out but does not seal against dust ingress. Pollution degree 3 rating means it is suited for industrial environments with conductive pollution, but the terminals themselves are IP00 — keep live parts guarded.
Fuse coordination and wiring
Type 2 coordination (no damage to the contactor under short circuit) requires a gL/gG fuse rated at 35 A maximum. Type 1 coordination (contactor may need replacement after fault) allows a 100 A gL/gG fuse. The screw terminals accept 2x (0.25–2.5 mm²) solid or 2x (1–2.5 mm²) stranded, with a maximum of 2x 10 mm² or a single 8 AWG. Strip length and torque values follow standard Siemens terminal practice — no special tooling needed.