What this assembly delivers — and what it fits
The Siemens 3RA2328-8XE30-1BB4 is a SIRIUS reversing contactor assembly in the S0 frame, rated at 38 A in AC-3 duty at 480 V and 18.5 kW at 400 V — meaning it handles reversing motor loads up to that current without external interlocks. The coil is 24 VDC, screw-type terminals on both the magnet coil and main circuit. The assembly ships with two contactors already fitted: a 3RT2028-1BB40-0CC0 and a 3RT2028-1BB40, plus the mechanical interlock kit 3RA2923-2AA1. That means it arrives ready to wire into a panel — no separate interlock sourcing, no alignment fiddling. The S0 footprint (90 mm wide, 101 mm high, 107 mm deep) fits the common panel layout; spacing to adjacent devices is 6 mm upward, forward, downward, and to the side, with zero clearance needed behind.
Sizing and duty — AC-3 vs AC-4
The headline AC-3 rating (38 A at 480 V, 18.5 kW at 400 V) is for standard squirrel-cage motor starting — the common case. For heavy-duty reversing or plugging duty (AC-4), the rating drops to 11 kW at 400 V. If your application involves frequent inching or reversing under load, size against the AC-4 figure, not the AC-3 number.
Wiring and terminal detail
Main circuit terminals accept solid conductors: 2x (1 to 2.5 mm²) and 2x (2.5 to 10 mm²). Stranded: 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²). AWG equivalents: 2x (16 to 12) and 2x (14 to 8). All screw-type — no spring-cage on this variant.