What it is and what it does
The Siemens SENTRON 3VA1150-5EF32-0AG0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection — meaning it sits upstream of a feeder or distribution panel, not on a motor branch. It carries a rated continuous current Iu of 50 A and uses a TM240 thermal-magnetic overcurrent release, so the thermal element handles overloads and the magnetic element handles short-circuits up to the breaker's interrupting capacity. The interrupting ratings are what make this breaker stand out: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. That 187 kA at 240 V is a high-fault rating — it means this breaker can safely clear a fault on a 240 V bus with up to 187 kA available fault current, which is typical for large transformer secondaries or industrial switchgear. At 690 V the rating drops to 17 kA, still enough for most 690 V distribution but worth checking against the available fault current at that voltage.
Thermal derating and operating range
The breaker holds its full 50 A rating from 40 °C through 50 °C ambient. Above that it derates: 48 A at 55 °C, 47 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. If your panel ambient runs above 50 °C, you need to account for that derating — the breaker won't trip falsely, but you lose headroom on the continuous load. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Dimensions and panel fit
The breaker measures 130 mm high, 76.2 mm wide, and 70 mm deep. That 76.2 mm width is a standard 3-pole MCCB footprint — it fits the same panel cutout and bus-bar spacing as other SENTRON 3VA 3-pole frames. The front face carries an IP40 protection rating, so it's fine for general indoor panel use but not for washdown or outdoor exposure.
Auxiliary contacts and trip indication
This version comes with one auxiliary switch and one trip alarm switch (HP type). The trip alarm switch changes state only when the breaker trips on a fault — useful for remote fault annunciation or a shunt-trip circuit. A trip indicator is also built into the front, so a walk-by inspection shows a tripped breaker without opening the panel door. The mechanical endurance is rated at 15 000 operations.