The 50 kA breaking capacity at 400 V per IEC 60947-2 is the headline number here: it safely interrupts a fault current up to 50,000 A without welding or exploding, which is essential for high-fault panels downstream of large transformers. At DC (72 V max) it still breaks 15 kA, so it works in DC control circuits too.
Thermal derating and environment
Rated 3 A at 45 °C ambient. At 50 °C it derates to 2.91 A; at 55 °C to 2.81 A.
The 5SY8103-7 carries the standard SENTRON compliance package: halogen-free and silicon-free construction, sealable for tamper-proofing, and designed per IEC 60947-2 with a 50 kA rated short-circuit capacity. It's marked for mechanical engineering / industry use per the manufacturer's suitability listing.