The Siemens 3VA1225-4GE42-0AA0-ZD00 is a 4-pole molded-case circuit breaker on the IEC frame 250 platform, rated In=250A with a TM220 thermal-magnetic trip unit. Its Icu of 36kA at 415V AC puts it in breaking capacity class S — that means it can safely interrupt a 36kA fault without needing an upstream current-limiting fuse, which simplifies coordination in a distribution panel. Overload protection is adjustable from Ir=175A to 250A via the TM220 dial, so you can fine-tune the trip point to the actual load without swapping the breaker body. Short-circuit protection is fixed at Ii=10 x In (2500A magnetic pickup), which is typical for line protection of cables and busbars rather than motor starting. The 100% N conductor protection means the neutral pole has its own overload and short-circuit sensing — not just a switched neutral. That matters for 4-wire systems where unbalanced neutral currents can reach fault levels. The nut keeper kit included suggests this variant is destined for a DC Power OEM assembly in China, but the breaker itself is a standard 3VA1 catalog part.
What the ratings mean for fit
The 36kA Icu at 415V is the ultimate breaking capacity — the breaker can clear one fault at that level and still be functional afterward. The TM220 trip is thermal-magnetic: the thermal element handles overloads (Ir adjustable 175-250A) with an inverse-time curve, and the magnetic element handles short-circuits (Ii fixed at 10xIn). Mounts on a standard DIN rail or panel-mount base. The 4-pole format with 100% N protection means it occupies four full pole widths in the enclosure — factor that into your panel layout.