Siemens 5SY4401-7 SENTRON miniature circuit breaker, 4-pole, 1 A rating, C-trip curve. It's the line-side protection for small three-phase loads like control transformers or VFD inputs where the fault level stays under 35 kA. The 35 kA breaking capacity per IEC 60947-2 covers high-fault panels; the 10 kA per EN 60898 runs the residential/commercial spec. Track which standard governs your panel — the UL1077 listing gives an additional commercial equipment path. At 40 °C ambient, the 1 A rating knocks down to 0.95 A; at 60 °C it's 0.85 A. If the panel runs hot, size up one frame or account for the curve.
Mounting and Installation
Four modular width units (72 mm wide) on the DIN rail. Mounts in any position; quick assembly system clips in without tools. The combined top and bottom terminals accept per-conductor wiring; sealable for lockout/tagout. IP20 with connected conductors — protect from direct contact but not from moisture.
Sourcing and Lifecycle
This is a current-production item. Place against a BOM line — I'll quote to order. No neutral switching on this 4-pole; the fourth pole is the switched phase only — verify if your panel expects a switched neutral.