Siemens 3VA1150-3EF32-0AB0 — 50 A SENTRON MCCB, Line Protection
At 240 V it interrupts 75.6 kA; at 415 V that drops to 52.5 kA, and at 690 V it still holds 11.9 kA. Those are high-interrupting ratings for a 50 A frame — it's sized for large transformer-fed or utility-tied distribution, not a sub-panel with limited fault current. Thermal-magnetic release means the thermal bimetal handles sustained overloads (minutes-to-hours curve) while the magnetic coil trips instantaneously on a hard short. The TM240 designation sets the magnetic pickup at 240 A (4.8× the 50 A rating), which is a standard curve for motor branch circuits and general distribution.
Fit and Mounting — Panel Integration
The 3VA1150-3EF32-0AB0 measures 130 mm tall, 76.2 mm wide, and 70 mm deep. The 70 mm depth keeps the breaker within typical gland-plate clearance on 200 mm-deep panels. Current derating starts above 55 °C: 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. If the panel runs hot — next to a drive or transformer — plan for the reduced ampacity. Power loss is 14.6 W maximum at rated load. That's moderate for a 50 A MCCB; it won't drive significant heat rise in a ventilated enclosure, but in a sealed panel with dense packing, account for it in the thermal budget.
That's the number you match to your load's full-load amps — a 50 A MCCB protects a 50 A feeder or a motor with a nameplate FLA under 50 A. The TM240 magnetic trip at 240 A handles motor inrush (typically 6-8× FLA for a few cycles) without nuisance trips. The 3-pole design switches all three phases simultaneously, which is standard for 3-phase line protection. If you need UVR, GFCI, or remote trip signaling, you'd step up to the 3VA2 or add external accessories. The auxiliary switch design includes 2 auxiliary switches HP for status indication.