Compact starter with 53 kA interrupting capacity
The Siemens 3RA6120-0BB30 is a SIRIUS compact starter — a direct starter that combines a contactor and overload relay in one 45 mm-wide housing. It's designed for continuous operation per IEC 60947-6-2, meaning it handles sustained motor starting duty without derating for intermittent use. For a panel builder, that number sets the available fault current ceiling on the line side; if your transformer or upstream breaker can deliver more than 53 kA at 400 V, you need a current-limiting device ahead of this starter.
Trip class and control voltage
The overload relay is adjustable between trip class 10 and 20. You set it with a dial on the front; no swapping heater packs. That's a single supply rail for the coil — common in modern panels with 24 VDC power supplies. Power dissipation is 2.8 W AC max and 2.9 W DC max, so the heat load in a densely packed enclosure is manageable.
DIN-rail footprint and environmental limits
Mounting position is any orientation, though the recommended position is vertical on a horizontal rail. That 45 mm width is the same as a typical 3-pole contactor, so it fits in a standard 45 mm slot on a DIN-rail layout. Operating temperature range is -20 to +60 °C, storage and transport from -55 to +80 °C. Pollution degree 3 means it's rated for industrial environments with conductive dust or occasional condensation — no need for a sealed enclosure unless the atmosphere is aggressively corrosive. Shock tested to 60 m/s² (6 g) for 10 ms pulses in all axes, and vibration tested to 4–5.8 Hz at 15 mm displacement and 5.8–500 Hz at 20 m/s² for 10 cycles. That's enough for machine-mounted duty on a conveyor or pump skid without a separate isolation mount.