Sizing the 3RA6120-1DB33 for the motor load
That 53 kA figure tells you the starter can survive a bolted fault at the motor terminals up to that level without the upstream breaker needing to clear first — useful when the panel SCCR requirement is high and you want to avoid a larger frame.
Mounting and wiring constraints
The starter mounts on standard 35 mm DIN rail, either vertical or horizontal, and uses both screw and snap-on fastening. The 45 mm width keeps the footprint tight — three of these fit in a standard 140 mm wide enclosure section. The main circuit connection is plug-in without terminals — the power contacts are on the backplane, so you wire the base unit once and the starter module plugs in. This matters for MRO: swap a failed starter in under a minute without disturbing the panel wiring.
Environmental and mechanical endurance
Rated for continuous operation per IEC 60947-6-2, the 3RA6120-1DB33 handles sustained motor duty without derating in ambient temperatures from -20 to +60 °C. Shock resistance is 6g for 10 ms in all axes, and vibration resistance covers 4 to 500 Hz at 20 m/s² — both figures confirm it holds up on a machine frame or conveyor line, not just in a climate-controlled cabinet. Power dissipation is 2.8 W AC maximum and 2.9 W DC maximum — negligible heat for a panel with forced ventilation, but worth noting if the enclosure is sealed and densely packed. The two onboard LEDs give local status indication for the control voltage and the output state, which speeds up fault-finding on the line.