The Siemens 5SY4314-7CV is a 3-pole miniature circuit breaker with a C-curve rated at 0.3 A and a breaking capacity of 15 kA at 400 V. The C-curve (5–10x In magnetic trip) suits it for mixed resistive and light inductive loads where moderate inrush is expected, not motor starting.
The 0.3 A rating is unusually low for a 3-pole MCB — this is a specialty breaker for protecting instrumentation, control transformers, or small-signal circuits where a standard 1 A or higher breaker would not trip on a low-current fault. Three poles with a shared C-curve mean all phases trip together on an overcurrent on any one pole, which matters for 3-phase control circuits where single-phasing could damage equipment.
Integration Notes
Mounts on standard DIN rail in the enclosure. The C0.3 curve is sensitive: verify the connected load's inrush characteristic stays below 1.5 A (5x rated) to avoid nuisance tripping. Panel fill factor is standard for a 3-pole MCB — 3 module widths (approx. 54 mm) on the rail.