The Siemens SIRIUS 3RV2131-4PA10 is a motor-protective circuit breaker with integrated overload relay function — one device does both short-circuit and overload protection for a motor branch. That keeps the line moving: a weld gun or conveyor motor gets fast enough protection without nuisance tripping on a normal start. The headline number is the breaking capacity: 100 kA at 240 V, 30 kA at 400 V, 5 kA at 500 V, 2 kA at 690 V. That's a real panel-design advantage — you don't have to oversize the feeder breaker or add current-limiting fuses for most line-side fault conditions. Rated operating voltage covers 20 to 690 V AC, so it handles everything from 230 V single-phase control transformers up to 690 V three-phase motor circuits. At 230 V it's rated for 7.5 hp, at 200/208 V for 15 hp, and at 480/600 V for 36 A — the horsepower and current ratings are voltage-specific, so match the motor nameplate to the right column. If you need ground-fault protection on the motor branch, add an external module or a separate GFP device.
The 75 mm width takes three standard 18 mm module spaces — factor that into your DIN-rail layout. Any mounting position is allowed, so vertical or horizontal rail orientation works. Depth 149 mm, height 140 mm, width 75 mm. Screw-type terminals accept 2× 1 to 25 mm² solid/stranded, or 1× 1 to 35 mm². M6 terminal screws.