Reversing motor starter with Class 10 bimetal protection
The Siemens 3RK4340-3PR51-1BA0 is a SIRIUS reversing motor starter, I/O controlled, designed for starting and stopping three-phase motors in both directions. Its reversing configuration means two contactors are interlocked inside the same enclosure, saving panel space over two separate starters.
AC-3 current rating and voltage range — what fits
The 12 A AC-3 at 400 V is the headline motor-switching rating. The operating voltage range is 340 to 440 V, covering 400 V nominal systems with typical tolerance. The control supply is DC, 20.4 to 26.4 V — a standard 24 VDC control bus works, but the lower threshold means a sagging supply down to 20.4 V still keeps the coil engaged.
Mounting and enclosure — IP55 for washdown areas
IP55 means the enclosure is dust-protected and protected against water jets from any direction — suitable for installation in areas where hosedown cleaning happens, like food processing or light industrial washdown zones. The dimensions are 145 mm deep, 182 mm wide, 220 mm high — a compact footprint for a reversing starter with built-in overload.
No UL or CSA listing is explicitly stated in the spec record, so verify with your local code requirements if those marks are mandatory.