The MGN60540 is a C60N miniature circuit breaker from the Multi9 range, 3-pole, D curve, rated 40 A at 50 °C per EN/IEC 60947-2. Breaking capacity is 20 kA Icu at 240 V AC phase-to-phase, 10 kA at 415 V AC, and 6 kA at 440 V AC — all per EN/IEC 60947-2. The service breaking capacity (Ics) is 75 % of those figures: 15 kA at 240 V, 7.5 kA at 415 V, 4.5 kA at 440 V. That means after clearing a fault at Ics level the breaker remains functional, not just safe. For a 240 V panel with high available fault current, this holds. The tunnel terminals accept 1.5 to 35 mm² rigid or flexible wire; torque to 3.5 N·m on the power circuit. IP20 finger-safe front, pollution degree 3 rated — standard for distribution boards in industrial enclosures.
D curve selection logic
The D curve trips magnetically at 12 x In (±20 %). For a 40 A circuit feeding a motor starter, this avoids nuisance tripping from starting current.
Integration into a distribution board
The 54 mm width (6 modules) means it occupies six 9 mm positions; plan your busbar and gland plate fill accordingly. Toggle handle with ON/OFF indication and a contact position indicator for visual isolation confirmation.