The Siemens 3RA2335-8XB30-1KB4 is a SIRIUS reversing contactor assembly, size S2, built around two 3RT2035-1KB40 contactors mechanically interlocked for forward/reverse motor control.
AC-3 duty ratings and what they mean for motor sizing
Rated 40 A at 480 V in AC-3 duty — that's the full-load motor current it can switch without welding contacts on inductive starts. At 400 V it's rated 18.5 kW, at 690 V still 22 kW, so the voltage ceiling is 690 V AC-3/AC-3e. Mechanical life is 10 million operations typical; the maximum switching rate is 1,000 cycles per hour in AC-3 or AC-3e duty, which covers most conveyor and pump reversing applications. Coil is 24 V DC with screw-type terminals — confirm the control voltage matches your PLC output card before wiring.
Panel fit and mounting — DIN rail with clearance specs
Dimensions are 120 mm wide, 141 mm high, 130 mm deep — that's the S2 contactor footprint. Required clearances: 10 mm upward, 10 mm forward, 10 mm downward, 10 mm at the sides, and 0 mm backward (flush to the rail). Main circuit terminals accept 2x (1...35 mm²) solid or 1x (1...50 mm²) — covers most motor feeder cables up to 50 mm².
Environmental limits and shock/vibration tolerance
Withstands 12g shock for 5 ms and 7g for 10 ms at DC — rated for industrial panel vibration environments.