The SENTRON 5SP4340-8 is a 3-pole miniature circuit breaker from the 5SP4 series, rated 40 A at 400 V AC with a D tripping characteristic.
D-curve and breaking capacity
The D characteristic means the magnetic trip fires at 10 to 20 times rated current — 400 to 800 A on this 40 A frame. That suits loads with high inrush: motor starters, transformers, welding equipment, or capacitor banks where a C-curve would nuisance-trip on energization. The 10 kA (EN 60898) covers residential and light commercial service entrance requirements; the 20 kA (IEC 60947-2) is the figure to use for industrial coordination studies under a 400 V supply.
The 70 mm depth leaves clearance for busbar comb bridges and downstream wiring in a typical 120 mm deep enclosure.