What this MCB is and where it fits
The Siemens 5SY7340-8 is a SENTRON miniature circuit breaker with a D tripping characteristic, three poles, and a 15 kA rated breaking capacity per EN 60898-1 (20 kA per IEC 60947-2). It's built for industrial control panels and machinery where high inrush currents — motor starts, transformer energization, welding equipment — would nuisance-trip a B or C curve. The D-curve holds through those surges and clears a hard fault when it counts.
Ratings that decide the fit
Breaking capacity is the headline: 15 kA under EN 60898-1 and 20 kA under IEC 60947-2. That dual rating means it's accepted in panels destined for European (EN) and international (IEC) specs, and it also carries UL 1077 / CSA C22.2 No. 235 recognition at 5 kA — enough for North American supplementary protection. The 400 V AC rated voltage (440 V max multi-phase) covers standard three-phase distribution; DC side is rated 60 V (72 V max) with 15 kA breaking capacity per IEC 60947-2. The D-curve characteristic is the key selection parameter for motor and inductive loads. It allows short-duration inrush up to 10–20× rated current without tripping, so a pump or compressor starting under load won't drop the line. For the MRO planner: if you're replacing a C-curve that nuisance-tripped on a motor start, this is the swap. Three-pole construction (3 MW units wide, 54 mm) with a 76 mm depth and 90 mm height. Mounts on DIN rail via the quick-assembly system in any position. Pollution degree 3 and overvoltage category III — rated for the dirty, transient-heavy environment inside an industrial enclosure.
Compliance and environmental notes
Halogen-free and silicon-free construction. Sealable with a lockable cover for lockout/tagout compliance. Operating temperature range -40 °C to 75 °C, with humidity derating above 55 °C. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz — survives the shake of a conveyor line or compressor skid.