SENTRON 5SY8220-7 — 2-pole C-curve MCB for industrial branch circuits
It occupies 2 modular width units (36 mm) on a DIN rail, rated to clear 30 kA at 400 V AC per IEC 60947-2 — that's the fault current it can safely interrupt without welding contacts or cascading upstream. For DC circuits it's rated 15 kA at 60 V, and under UL 1077 it carries a 5 kA interrupting rating.
Standards and approvals — what the ratings certify
This breaker carries dual certification: IEC/EN 60947-2 (the international standard for industrial circuit breakers) and UL 1077 (supplementary protector for North American panels). The UL 1077 rating of 5 kA at 400 V AC reflects the different test protocol for supplementary protectors; it's not a derating, it's a different standard. For DC circuits it's rated 15 kA at 60 V per IEC 60947-2.
Panel integration — dimensions and mounting
Width 36 mm (2 MW), depth 76 mm, height 90 mm. Installation depth 70 mm — the extra 6 mm beyond the body accounts for the terminal screws and wiring space. IP20 with connected conductors (finger-safe only when wired; not for wet environments). Sealable with a lockable cover for tamper-proof isolation.
Environmental limits and service life
Ambient temperature range -40 °C to +75 °C, but the humidity derating curve matters: max 95% RH at 55 °C, dropping to 55% at 70 °C and 35% at 75 °C. In a sealed cabinet near a heat source, that's the limit that governs — not the dry-air temperature spec. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz. Mechanical service life 10,000 operating cycles typical — adequate for branch-circuit protection where the breaker is cycled infrequently; not rated for frequent switching duty.