What this MCCB is and where it fits
The Siemens SENTRON 3VA1150-4EF32-0KC0 is a 3-pole molded case circuit breaker (MCCB) rated for 50 A continuous current at 40 °C, with a TM240 thermal-magnetic overcurrent release and an integrated shunt trip (STL) auxiliary release. It's a line-protection device — meaning it's set up for feeder and distribution duty, not motor branch-circuit protection. The 800 V rated insulation voltage (Ui) gives it headroom for panel applications without derating the insulation system. The 70 mm depth, 76.2 mm width, and 130 mm height footprint fits standard SENTRON 3VA panel cutouts and bus-bar layouts. The IP40 front protection means it's fine inside a closed enclosure — not for washdown areas.
Breaking capacity — what the numbers mean for selectivity
This MCCB delivers 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V. Those are the interrupting ratings (Icu) at each voltage level — the fault current it can safely clear without welding or rupturing. For a 480 V panel fed from a 100 kA transformer, the 52.5 kA at 440 V tells you this breaker has headroom for most common fault levels at that voltage. At 690 V, the 11.9 kA rating is lower but still sufficient for many industrial distribution scenarios where the available fault current is kept under 10 kA.
Current derating — the real-world continuous current
The 50 A rating holds flat from 40 °C up to 50 °C — no derating needed in a typical warm panel. At 55 °C it drops to 48 A, at 60 °C to 47 A, at 65 °C to 46 A, and at 70 °C to 45 A. If your panel ambient runs above 50 °C, size the load accordingly. The TM240 release is a thermal-magnetic type with a fixed thermal element calibrated for 50 A at 40 °C; the magnetic pickup is fixed as well, so coordination studies should use the published trip curves.
Auxiliary contacts and shunt trip
The breaker comes with 2 auxiliary switches (HQ type) for status feedback — open/closed indication to a PLC or remote monitoring system. The shunt trip (STL) allows remote tripping via a control voltage, useful for emergency-stop circuits or supervisory shutdown. No undervoltage release, no ground-fault monitoring, no communication module, no phase-failure detection on this variant — it's a straightforward distribution breaker with basic remote-trip capability.