The Siemens SENTRON 5SJ4314-8HG41 is a 3-pole miniature circuit breaker with a D tripping characteristic, rated at 0.3 A at 30 °C. It's part of the 5SJ4 series, designed for DIN-rail mounting in control panels and distribution boards. At 0.3 A, it's sized for small control transformers or signal circuits, not main power feeds.
The D characteristic provides a magnetic trip threshold of 10 to 20 times the rated current, so this 0.3 A breaker will hold through short-duration surges up to roughly 3 to 6 A before the magnetic coil reacts. That's the right choice for a small control transformer or a relay coil bank where the inrush is brief but high. The thermal element handles the continuous overload side — at 40 °C it still carries the full 0.3 A, but at 60 °C it derates to 0.25 A. Rated for AC/DC operation with a maximum DC voltage of 60 V. That covers most 24 VDC control circuits and 48 VDC telecom supplies, but not a 125 VDC battery bank. The housing carries IP20 with connected conductors, and IP40 in the handle range. That's standard for a DIN-rail MCB inside a closed panel — no special washdown rating. If the breaker is mounted where operators can touch the handle, the IP40 on the toggle is enough for accidental splashes, but not hose-down.
Sealable — you can wire a seal through the housing to prevent tampering, which matters for revenue-grade metering or safety-critical circuits where the breaker setting must stay locked. Halogen-free and silicon-free construction reduces toxic smoke and corrosive byproducts in a fault scenario, a consideration for enclosed switchgear or clean-room adjacent panels.