The Siemens 5SY8340-7 is a SENTRON miniature circuit breaker in a 3-pole configuration with a C-tripping characteristic, designed for branch-circuit protection in industrial control panels. Its 25 kA rated breaking capacity at 400 V AC per IEC 60947-2 means it can safely interrupt a fault current up to that level without upstream fuses needing to clear — a key selectivity consideration when coordinating with a main breaker or switchgear. The C-curve (magnetic trip between 5× and 10× In) suits motor and transformer loads where inrush is moderate, typical for mechanical engineering and industrial applications.
Standards & Compliance
Rated per IEC / EN 60947-2 and UL1077, the 5SY8340-7 carries a 25 kA interrupting rating at 400 V AC (IEC) and 5 kA per UL 1077 / CSA C22.2 No. 235. At DC it is rated 15 kA at 60 V, with a maximum operating voltage of 72 V DC. The enclosure is IP20 with connected conductors — suitable for enclosed panel mounting, not for wet or outdoor locations without a secondary enclosure. The part is halogen-free and silicon-free, which matters for sensitive environments like data centers or clean rooms where outgassing can affect contacts or optics.
Mounting & Dimensions
Snap-on mounting to DIN rail via the quick assembly system; mounting position is any, which simplifies panel layout. The 54 mm width (3 modular units) and 76 mm depth fit standard distribution boards. Combined terminals top and bottom accept copper conductors without neutral switching — the neutral bar stays continuous through the breaker. Installation depth of 70 mm leaves clearance for wiring behind the rail.