The MGN61818 is a Schneider Electric Multi9 C60H-DC miniature circuit breaker rated 25 A at 50 °C per EN/IEC 60947-2, with 2 protected poles and a B curve (magnetic trip at 5.5 x In ±20% DC). This is a DC-rated breaker — the network type is DC, and the breaking capacity reaches 20 kA Icu at 220 V DC, 20 kA at 250 V DC, 10 kA at 440 V DC, and 6 kA at 500 V DC. The thermal-magnetic trip unit handles the overcurrent and short-circuit protection for DC distribution circuits.
The 20 kA breaking capacity at 220 V DC is the headline number — it tells you this breaker can safely interrupt a fault current up to 20,000 A on a 220 V DC bus without welding or exploding. That is a high-interrupting rating for a 2-pole DC breaker, suited for battery banks, DC motor drives, or solar combiner boxes where fault currents can be stiff. The B curve means the magnetic trip fires at 3.2 to 5.5 x In (roughly 80 to 137.5 A for this 25 A unit), which is fast on moderate overloads — good for resistive or lightly inductive DC loads, but not for high-inrush loads like DC motor starters (those would need a C or D curve).
Deployment context
The IP20 finger-safe terminals (IP40 on the modular enclosure) mean it is intended for dry indoor locations — not washdown or outdoor exposure. The tunnel-type terminals accept up to 25 mm² rigid stranded (AWG 4) or 16 mm² flexible; strip 14 mm and torque to 2.5 N.m. The toggle handle gives local ON/OFF indication and is padlockable for lockout/tagout.