Panel fit and trip curve
The Siemens 5SL6640-7CC is a SENTRON miniature circuit breaker (MCB) rated 40 A at 30 °C with a C-curve trip characteristic, meaning it trips at 5–10 times rated current — the standard choice for motor starters, transformers, and general branch circuits where moderate inrush is expected. Rated 400 V AC for multi-phase operation, with a maximum operating voltage of 440 V AC. The DC side is rated 72 V maximum — useful for control circuits but not the primary application. Derating is specified: at 40 °C ambient the breaker carries 37.72 A, at 50 °C it drops to 35.3 A, and at 55 °C it is 34.02 A. If the panel runs warm, size the upstream protection accordingly.
Sealable, halogen-free, and silicon-free construction, which matters for clean-room or food-processing zones where off-gassing must be controlled. Vibration resistance rated at 50 m/s² from 25 to 150 Hz per IEC 60068-2-6 — adequate for most fixed installations but not for continuous shock on mobile equipment.