The Siemens 5SJ4318-8HG41 is a SENTRON 5SJ4 miniature circuit breaker — 3-pole, D tripping curve, rated 400 V AC and 60 V DC.
The D characteristic is the headline here — it's designed for circuits where the starting current can briefly hit 10–14 times the rated current before settling. That makes it a better fit for motor feeders, welding equipment, and heavy inductive loads than a B or C curve breaker, which would trip on the same inrush. Insulation voltage is rated at 440 V AC, so it's fine for 400 V line-to-line systems with margin. The 70 mm depth (installation depth matches) and 54 mm width (3 modular units) are the panel-fit dimensions you need for enclosure layout. It's sealable, halogen-free, and silicon-free — relevant for food, pharma, or clean-room environments where outgassing or contamination is a concern.