The Siemens 3VA1225-5GF42-0JA0 is a 4-pole IEC frame 250 molded case circuit breaker with a 55 kA interrupting capacity at 415 V (breaking capacity class M). It's built for line protection with a TM240 thermal-magnetic trip unit — the thermal element adjustable from 175 A to 250 A, the magnetic pickup set at 5 to 10 times In. That means you can dial in the overload protection to match your cable or busbar rating, while the short-circuit trip stays fast enough to clear a bolted fault without letting the arc sustain. This unit also includes a shunt trip (STL) rated for 110–127 V DC or AC, 50/60 Hz. That's the remote-trip coil — tie it to an E-stop button, a fire alarm relay, or a PLC digital output, and you can drop the breaker from a distance without walking to the panel. The 100% neutral conductor protection means the neutral pole is fully rated, not just a switched neutral.
Lifecycle stage is current — this is an active-production part from Siemens. No phase-out notice, no last-time-buy window to watch. For a BOM freeze, this breaker is a stable line item; you're not chasing a sunset date.
Panel fit & integration
Mounts in a standard switchboard or enclosure on a mounting plate — no DIN rail for this frame size. The 4-pole footprint needs roughly 280 mm of panel width; leave clearance above for the arc-chute exhaust and below for the shunt-trip wiring. Spring-cage terminals on the load side accept 50–185 mm² cable; torque per the nameplate values.