It's a Type A instantaneous unit — meaning it catches sinusoidal AC and pulsating DC residual currents, no time delay, so it's the go-to for general-purpose shock protection in distribution boards. Surge current resistance is 1 kA, surge voltage resistance 4 kV, so it holds up against switching transients and indirect lightning strikes without nuisance tripping.
Thermal derating — the real-world rating
The 40 A headline rating holds at 40 °C ambient. Above that, the unit derates: 37.2 A at 45 °C, 36 A at 50 °C, 34.8 A at 55 °C, 34 A at 60 °C, 33.2 A at 65 °C, and 32 A at 70 °C.
Occupies 3 modular width units (17.5 mm each = 52.5 mm total) on a DIN rail. Depth is 70 mm, width 105 mm, height 90 mm. Mounting position is any orientation; supply can enter top or bottom. Fastening is standard REG (regular) clip-on. Not sealable, and the OFF-delay is fixed (no adjustable time delay). Rated fault current is also fixed at 30 mA — no adjustment dial. This is a straight swap-in for a 5SL4-series RCD; the product variation field confirms it's designed for that family.