The Siemens 5SP3840-2XX31 is a SENTRON 5SP3 main miniature circuit breaker — the SHU type, three-pole, rated 40 A with an E tripping characteristic. It mounts on a 40-mm busbar system per DIN 43870 Part 2.
Terminal and integration details
Solid and stranded conductors from 2.5 mm² up to 50 mm² are accepted — that's a wide lugging range that covers most meter-panel feeds without needing reducers. The outgoing side uses a spring-loaded terminal, so the load cables get a vibration-resistant grip without retorquing. Infeed is at the box terminal, and the design allows sealing (locking slide, wire seal, cable ties, Antilux) for revenue-meter applications where tamper evidence matters.
Storage range goes -40 to +70 °C — that's the shipping and warehousing limit, not the running condition. Shock resistance is 30 g for at least 3 impacts at 11 ms duration; vibration per IEC 60068-2-6 is 2 g over 5 to 150 Hz. Those numbers tell you it holds up to the bumps of transport and occasional seismic events, but it's not a rail-traction or shipboard-rated device. Mechanical life is 20 000 switching cycles typical — enough for a main breaker that operates a few times a year, not a frequent-switching load contactor.