What this MCCB is and what the ratings mean
The Siemens SENTRON 3VA1125-5EF32-0CA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a TM240 thermal-magnetic overcurrent release. The 25 A continuous rating holds across 40 °C to 50 °C ambient, then derates to 24 A at 55–60 °C and 23 A at 65–70 °C — so in a warm panel you lose about 2 A, not the full rating. The interrupting capacity is the headline: 187 kA at 240 V AC, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. That 187 kA at 240 V means this breaker can safely clear a fault up to that level without rupturing — critical for high-fault-capacity service entrances or transformer secondaries where available fault current is high.
Built-in undervoltage release and insulation rating
This variant includes an undervoltage release (UVR) — if the control voltage drops below the dropout threshold, the breaker trips, protecting downstream equipment from brownout damage. The insulation voltage is rated 800 V, so the breaker is suitable for 480/277 V and 600 V systems with margin. The TM240 release is thermal-magnetic: the thermal element handles overloads (slow trip on sustained overcurrent), the magnetic element handles short-circuit (instantaneous trip above a set threshold). No ground-fault monitoring, no communication function, and no voltage-trigger or trip indicator — this is a straightforward thermal-magnetic MCCB with UVR, not a smart breaker.
Physical fit and panel integration
The breaker measures 130 mm high, 76.2 mm wide, 70 mm deep. That 76.2 mm width is three 25.4 mm pole spacings — standard for a 3-pole MCCB on a DIN rail or panel-mount base. The 70 mm depth means it fits in a 200 mm deep enclosure with room for wiring and the UVR coil. Power loss is 11 W maximum, so heat dissipation is modest — no forced cooling needed in a typical panel. Operating temperature range is -25 °C to 70 °C; storage range -40 °C to 80 °C.