Siemens 5SJ4301-8HG41 SENTRON MCB, 3P, D-curve, 10kA

The D-curve means the magnetic trip coil engages at 10 to 20 times the rated current — typical for motor circuits where starting current can hit 8–12× FLA. At 400 V AC (the rated operational voltage), the breaker safely interrupts a 10 kA fault under EN 60898 rules, or 15 kA under IEC 60947-2, which governs industrial rather than household installations. Insulation voltage (Ui) is 440 V AC, so it suits 400 V line-to-line systems with margin. The DC rating of 60 V means it can also protect a 48 V DC control bus, but the 3-pole design does not switch the neutral — that's a separate pole if needed.