Reversing Contactor Assembly for Motor Control
The Siemens SIRIUS 3RA2335-8XB30-1NB3 is a factory-assembled reversing contactor assembly built around two 3RT2035-1NB30 contactors on a common S2 frame. It delivers 18.5 kW at 400 V AC-3 (40 A at 480 V, 22 kW at 690 V), sized for reversing motor loads up to 690 V AC-3 maximum.
The 18.5 kW at 400 V AC-3 rating governs motor switching capacity — this assembly handles reversing duty for a 3-phase induction motor up to that power without derating. The 40 A at 480 V and 22 kW at 690 V extend the same capability to North American and 690 V industrial grids. The S2 frame size matches the standard Siemens contactor footprint; the supplied contactors (3RT2035-1NB30) are mechanically interlocked for reversing, so no external interlock wiring is needed. The screw-type terminals on the main circuit accept 2x (1...35 mm²) solid or 1x (1...50 mm²) — sized for the motor branch circuit conductors this assembly controls.
Mounting and Wiring Considerations
The screw-type coil terminals accept 2x (0.5...1.5 mm²) or 2x (0.75...2.5 mm²) solid/stranded. Clearance requirements: 10 mm upwards, forwards, downwards, and to the side; 0 mm backwards (flush to the DIN rail).