This Siemens SENTRON 5SY8416-8 is a 4-pole miniature circuit breaker with a D tripping characteristic, rated 30 kA at 400 V AC per IEC 60947-2 and 15 kA at 60 V DC. The D-curve means it handles high inrush currents from motor or transformer loads without nuisance tripping — the magnetic trip kicks in at 10 to 20 times rated current, so it's the go-to for drives and welding gear, not lighting or general distribution.
The 15 kA at 60 V DC covers DC bus or battery-backed loads. The D-curve (tripping characteristic class D) is the key selection parameter here. Magnetic trip between 10× and 20× In means it ignores the startup surge of a motor or a power supply — you won't get a false trip on a cold start.
The 72 mm width (4 modular units) is standard for a 4-pole MCB; it occupies the same slot as any other 4-module wide device. Sealable with a lead seal or sticker for tamper-evident panels.