What it is and what it does
The Siemens 5SL7304-7RC is a 3-pole miniature circuit breaker (MCB) rated 415 V with a 15 kA breaking capacity and a C-curve trip characteristic at 4 A. The C-curve means it trips between 5 and 10 times rated current — standard for protecting inductive loads like motor starters, contactor coils, and small transformers where inrush is higher than a resistive load but not extreme. The 15 kA breaking capacity at 415 V tells you it can safely interrupt a fault current up to that level without welding contacts or cascading an arc upstream — critical for panel coordination studies.
Where it fits in a panel
Standard DIN-rail mount, 3-pole width. The 4 A rating with C-curve makes it a natural fit for protecting a small contactor coil circuit, a 24 VDC power supply primary side, or a control transformer secondary — anything where the inrush is a few times the steady current but not a motor direct-on-line start. The 15 kA SCCR at 415 V gives headroom for most commercial and light industrial distribution boards without needing a current-limiting upstream device.