What this MCCB is and what it does
The Siemens SENTRON 3VA1150-3EF32-0KC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying 50 A continuously at 40 °C ambient and delivering a 75.6 kA interrupting capacity at 240 V — enough to handle high-fault utility feeds or transformer secondaries without cascading upstream. The 800 V rated insulation voltage covers most 480/277 V and 600 V distribution panels with headroom. This is a current-production part in the SENTRON family, built for panel builders who need a compact, high-interrupt MCCB with integrated auxiliary switching and shunt trip capability.
Breaking capacity across voltages — what it means for your panel
The interrupting ratings are voltage-sensitive: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 11.9 kA at 500 V and 690 V. That 75.6 kA figure at 240 V is typical for a high-capacity MCCB on a low-voltage secondary — it safely clears a bolted fault on a large transformer without the breaker welding or rupturing. At 690 V the 11.9 kA rating still covers most industrial motor branch circuits; if your available fault current at that voltage exceeds 11.9 kA, you need a current-limiting upstream device or a higher-rated frame.
Thermal derating and power loss
The breaker holds 50 A from 40 °C through 50 °C ambient, then derates smoothly: 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, down to 45 A at 70 °C. If your panel runs hot — say 60 °C internal ambient — you lose 2 A of headroom. Maximum power dissipation is 14.6 W, which is modest for a 50 A MCCB; adjacent devices in a crowded enclosure won't see significant additional heat load. Operating range is -25 °C to 70 °C; storage range extends from -40 °C to 80 °C.
Auxiliary switching and shunt trip — what's inside
This variant ships with 2 factory-fitted auxiliary switches (HQ design) and a shunt trip (STL) release. That means you get remote status indication (open/closed/tripped) on two independent contacts, plus a remote trip coil that can be triggered by a safety relay, PLC output, or emergency-stop button. No undervoltage release is fitted, and there is no ground-fault monitoring module — if you need UVR or GF protection, you add them as external accessories or pick a different suffix. The auxiliary release is wired separately from the main load circuit; the shunt trip coil voltage must match your control voltage — verify polarity and coil rating before commissioning.