What it is and what it does
The Siemens 3VA1125-3EF32-0HH0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection — the primary protective device in a distribution panel, not a motor starter or feeder switch. It carries a continuous current rating of 25 A at 40 °C, with a slight derating curve: still 25 A at 50 °C, 24 A at 60 °C, and 23 A at 70 °C. The 3-pole construction handles three-phase circuits up to 800 V rated insulation voltage. Interrupting capacity is what decides whether this breaker survives a fault without welding its contacts. At 240 V it breaks 75.6 kA; at 415 V it breaks 52.5 kA; at 440 V it drops to 32 kA; at 500 V and 690 V it holds at 11.9 kA. That spread means the same breaker can serve a 480 V panel with moderate fault current or a 240 V service with very high available fault current — useful when standardizing one part number across multiple voltage levels.
Panel integration and physical fit
The breaker measures 130 mm high, 76.2 mm wide, and 70 mm deep — a compact 3-pole MCCB footprint that fits standard distribution panelboards. The 70 mm depth is the dimension that matters when the panel door clearance is tight; it leaves room for wiring and auxiliary accessories behind the trim. Maximum power loss is 8.5 W — relevant for thermal budgeting inside a sealed enclosure. The operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C.
Auxiliary and trip features
The breaker includes a trip indicator and a voltage trigger (shunt trip release, STL) as standard. It also carries two auxiliary switches plus one trip alarm switch (HQ). There is no undervoltage release, no communication function, no ground-fault monitoring, and no other measurement function — this is a straight line-protection device without add-on modules. The supplied basic switch variant is 3VA11253EF320AA0 — the core switching mechanism inside the molded case. That internal part number matters if you are cross-referencing a replacement for the internal assembly, though in practice the complete breaker is the ordered unit.