Siemens 5SY7420-7 — 4-pole C-curve MCB for panel builds
The Siemens 5SY7420-7 is a 4-pole miniature circuit breaker from the SENTRON series, rated 400 V AC with a C tripping characteristic. It carries a 15 kA breaking capacity per EN 60898-1 and 25 kA per IEC 60947-2, so it handles high-fault-current panel feeds without cascading upstream — the 25 kA figure is the one that governs industrial distribution board coordination. At DC the part is rated 15 kA at 60 V (max 72 V), which covers control-circuit protection in battery-backed or rectifier-fed sections. The C-curve (5–10× In) suits motor-starting and transformer inrush loads common in mechanical engineering and industrial environments. The breaker occupies 4 modular-width units (72 mm wide) on a DIN rail and snaps on via the quick-assembly system — no tools needed for mounting. IP20 with connected conductors means it is protected against finger contact once wired, standard for enclosed panel installation. Pollution degree 3 and overvoltage category III qualify it for fixed industrial installations where conductive dust or humidity is present.
Standards and compliance documentation
The breaker is certified to IEC / EN 60898-1, IEC / EN 60947-2, and UL 1077 / CSA C22.2 No. 235 (5 kA under UL/CSA). It is halogen-free and silicon-free, which matters for clean-room or semiconductor-fab panels where outgassing can contaminate optics or sensitive electronics. The manufacturer provides RoHS and REACH declarations as part of the standard documentation package; a UL/CSA mark is present on the nameplate.