The Siemens SIRIUS 3RA6250-1DB32 is a compact reversing starter — a single device that combines a reversing contactor pair and overload relay in one 90 mm wide housing, rated for continuous operation per IEC 60947-6-2. For a panel builder, that means it can be placed on a supply with a prospective short-circuit current up to 53 kA without needing a separate current-limiting fuse or breaker ahead of it, provided the upstream device is coordinated. The overload relay section offers adjustable trip class 10 and 20, so you can match the thermal curve to the motor start profile — class 10 for fast-starting pumps or fans, class 20 for high-inertia loads like centrifuges or crushers that need a longer acceleration ramp without nuisance tripping.
At 90 mm wide, 170 mm high, and 165 mm deep, this reversing starter occupies a single DIN-rail slot width typical of a four-pole contactor footprint. The screw-type terminals on the main circuit accept solid conductors from 0.5 to 4 mm², or two conductors of 0.5 to 2.5 mm² each — useful for daisy-chaining control wiring or paralleling power feeds without extra terminal blocks. Mounting position is any orientation, though the manufacturer recommends vertical on a horizontal standard DIN rail for optimal heat dissipation. The device is rated for continuous operation, so no derating for duty cycle is needed in normal motor-starting applications. Three integrated LEDs provide local status indication — useful during commissioning or fault finding without needing a multimeter on the terminals.
It is rated for shock resistance of 60 m/s² (6 g) over 10 ms per three shocks in all axes, and vibration resistance from 4 to 5.8 Hz at 15 mm amplitude, then 5.8 to 500 Hz at 20 m/s² for 10 cycles — figures that suit it for installation on machinery or in mobile equipment where mechanical stress is present.