Siemens 5SY3025-6KL SENTRON MCB — 25 A, B-Curve, 1P+N
The Siemens 5SY3025-6KL is a SENTRON miniature circuit breaker rated 25 A at 230 V AC, with a B-curve tripping characteristic and a breaking capacity of 4.5 kA per EN 60898. The 1-pole+N configuration switches both the phase and neutral, with neutral switching built in — no separate neutral block needed.
The B-curve (IEC 60898) means the magnetic trip activates at 3–5× rated current, so for a 25 A breaker the instantaneous trip window is roughly 75–125 A. That is fast enough to clear a hard short without nuisance tripping on the mild inrush of a resistive heater bank or a string of LED drivers, but it will trip on the starting current of a small motor — that is the intended selectivity boundary. If your load is a pump or compressor, step up to a C-curve sibling in the same SENTRON 5SY family. If your point of common coupling is close to a large transformer (fault current above 6 kA), you need the 6 kA variant — the 5SY6020-7KL or 5SY6010-6KL, which share the same footprint but carry a higher interrupting rating.
Panel Fit and Mechanical Notes
Dimensions are 90 mm high, 76 mm deep, and 18 mm wide — a single-module footprint that fits any standard 35 mm DIN rail enclosure. The screw terminals accept solid or stranded conductors up to 16 mm², with a tightening torque range of 17.7 to 22.1 lbf·in. The breaker is sealable, which allows a panel builder to lock the toggle position after commissioning to prevent unauthorized switching.