Siemens 5SY4210-6 SENTRON MCB — 2-Pole B-Curve, Dual-Rated Breaking Capacity
It is rated for 10 kA breaking capacity per IEC 60898-1 and 20 kA per IEC 60947-2, meaning it can safely interrupt fault currents up to 20 kA in industrial panel applications where the higher standard applies. The 400 V AC rating covers most three-phase distribution, while the 60 V DC rating (72 V max) handles control-circuit protection. This is a current-production part — no lifecycle concerns for a BOM freeze.
Don't use it for motor-starting duty where D-curve is needed. The dual breaking capacity (10 kA per IEC 60898-1, 20 kA per IEC 60947-2) means this breaker meets both residential and industrial standards; the 20 kA figure is the one that matters for a 400 V industrial panel with high fault current available. The DC rating of 15 kA per IEC 60947-2 covers DC distribution up to 72 V. The quick-assembly system and any-position mounting simplify panel layout.
Standards and Approvals — What They Certify
This MCB carries approvals under IEC 60898-1 (household-type MCB), IEC 60947-2 (industrial circuit-breaker standard), and UL 1077 / CSA C22.2 No. 235 (supplementary protectors for North America). The UL 1077 rating is 5 kA at AC — that's the supplementary protector rating, not the full branch-circuit rating. Halogen-free and silicon-free construction means no corrosive off-gassing in a sealed enclosure.