Breaking capacity across three standards
The 5SY4203-5: For DC circuits the interrupting rating drops to 15 kA per IEC 60947-2 at 60 V DC (72 V DC max operating voltage).
A-curve trip and what it means on the line
The A-curve characteristic (tripping class A) means the magnetic trip threshold is set at 2 to 3 times rated current — lower than the more common B-curve (3–5×) or C-curve (5–10×). This makes the 5SY4203-5 the right choice for protecting semiconductor loads, control transformers, or sensitive electronic circuits where the inrush is minimal and you need fast clearing on a short-circuit. On a panel feeding PLC power supplies or instrumentation loops, the A-curve avoids nuisance trips that a C-curve would cause on the same fault current.
At 36 mm wide (2 modular width units), 90 mm tall, and 76 mm deep (70 mm installation depth), this breaker occupies two standard 18 mm DIN-rail slots. The quick-assembly fastening system snaps onto the rail without tools. Mounting position is any orientation — no derating needed for horizontal or inverted placement.