DC-rated MCB for photovoltaic and small commercial strings
The Schneider Electric A9N61660 is a C60PV-DC miniature circuit breaker, 2-pole, rated 25 A with a B curve, designed specifically for DC circuits up to 800 V. It is built to EN/IEC 60947-2, Category A, meaning it provides short-circuit protection without intentional delay — the B curve trips magnetically at 3–5× In (here 5.5× In per spec), fast enough to protect PV string cabling and DC distribution from hard faults. Breaking capacity is 3 kA Icu at 650 V DC and 1.5 kA Icu at 800 V DC, with matching Ics at 100 % for service continuity. That covers typical residential and small commercial PV arrays where available fault current stays under 3 kA; for larger commercial strings or battery banks with higher prospective current, verify coordination upstream. Polarity-insensitive — it protects against bi-directional current, a must for battery storage where charge and discharge flow in opposite directions. No separate polarity marking needed on the line/load side.
Snaps onto 35 mm symmetrical DIN rail. Occupies 8 module pitches (9 mm each = 72 mm wide), so it fills 8 TE in a distribution board. Depth is 77.4 mm, height 132.7 mm — check enclosure depth clearance, especially in shallow consumer units or compact combiner boxes. Strip length 14 mm, torque to 2.5 N·m. Padlockable in OFF position for lockout/tagout.
Environmental and durability
Pollution degree 2 (normal indoor environments). Relative humidity tolerance 95 % at 55 °C. Mechanical durability 20,000 cycles; electrical durability 1,500 cycles at L/R = 2 ms — sufficient for switch-disconnect duty in PV combiner boxes where cycles are infrequent. Contact position indicator visible on the toggle.