What you're looking at
That characteristic A means it trips between 2 and 3 times rated current — tight, fast — so it's the go-to for protecting semiconductor circuits, control transformers, and sensitive electronic loads where a standard B or C curve would let through too much energy before opening. Breaking capacity is 10 kA per EN 60898 and 20 kA per IEC 60947-2 — the higher figure under the industrial standard means it can sit in a panel with a 20 kA prospective fault current at the bus, no problem.
Thermal derating — the real-world current
The 25 A rating holds at 35 °C ambient. At 40 °C it's 23.8 A; at 50 °C it's 22.55 A; at 60 °C it's 21.2 A. Humidity derating also applies: max 95% RH up to 55 °C, then drops to 55% at 70 °C and 35% at 75 °C.
Snap-on quick assembly system to DIN rail, any mounting position. IP20 with conductors connected; touch protection built in.