Star-delta contactor assembly — what ships inside
The 3RA2426-8XH32-1BB4 is a Siemens SIRIUS pre-assembled star-delta (wye-delta) contactor set for reduced-voltage starting of three-phase motors. It ships with three contactors: two 3RT2027-1BB40-0CC0 units and one 3RT2026-1BB40, plus the RS assembly kit 3RA2923-2BB1.
Mounting and panel fit
Size S0 frame, 135 mm wide × 101 mm high × 181 mm deep. Clearance around the unit: 6 mm upwards, forwards, downwards, and to the side; 0 mm backwards (the DIN rail face). The 181 mm depth means the assembly protrudes well into the enclosure — budget for gland-plate clearance and cable bend radius behind the door.
Termination and wiring
All connections — main current circuit, auxiliary/control circuit, and magnet coil — use screw-type terminals. Main circuit accepts solid conductors: 2× (1…2.5 mm²) and 2× (2.5…10 mm²). The manufacturer specifies gG NH 3NA, DIAZED 5SB, or NEOZED 5SE fuses at 50 A for type 2 coordination — this is the short-circuit protection rating that keeps the starter operational after a fault, not just safe. Wire the line side through these fuses before the contactor assembly.
Environmental and mechanical limits
The 60 °C ceiling is typical for enclosed panels — above that, derate the continuous current per the SIRIUS application manual. Shock resistance: 13.5 g / 5 ms and 8.3 g / 10 ms on AC; 15 g / 5 ms and 10 g / 10 ms on DC. Mechanical life of the typical contactor is 10 million operations. Maximum switching rate in AC-3 is 1,000 operations per hour — above that the contact erosion accelerates and the thermal capacity of the arc chamber becomes the limiting factor.
Lifecycle and sourcing
The magnet coil draws 13.8 W at DC rated value of 24 V — confirm the control transformer sizing if multiple starters share a common DC supply. Substance prohibitance date is 10/01/2009, aligning with RoHS compliance.