The Siemens 3RA2337-8XE30-1NB3 is a SIRIUS reversing contactor assembly — a factory-wired pair of contactors with mechanical and electrical interlock, ready to reverse a three-phase motor without external interlocking wiring. It ships with two 3RT2037 contactors: one with a suppressed coil (3RT2037-1NB30-0CC0) and one standard (3RT2037-1NB30). The assembly is rated for motor switching in AC-3 duty up to 690 V, delivering 30 kW at 400 V and 37 kW at 500 V and 690 V. At 480 V it carries 65 A; at 600 V, 62 A.
Dimensions are 120 mm wide, 141 mm high, 130 mm deep. Minimum clearance around the assembly: 10 mm upwards, forwards, downwards, and to the side; 0 mm backwards. Main circuit and coil connections use screw-type terminals; the main circuit accepts solid conductors up to 2× (1…35 mm²) plus an additional 1× (1…50 mm²), and stranded conductors 2× (0.5…1.5 mm²) and 2× (0.75…2.5 mm²). Two instantaneous auxiliary contacts are built in.
Mechanical life of the contactor typical is 10,000,000 operations. Maximum switching frequency in AC-3 and AC-3e duty is 700 cycles per hour. Vibration resistance: 12 g at 5 ms, 7 g at 10 ms (AC). Power factor at 50 Hz is 0.36; at 60 Hz, 0.39.