The Siemens SENTRON 5SL5120-7RC is a 1-pole miniature circuit breaker (MCB) with a C tripping characteristic, rated 20 A at 220 VDC and a breaking capacity of 10 kA. This is a DC-rated MCB, not the more common AC version — the 220 VDC rating makes it suitable for DC distribution in telecom, solar combiner boxes, or industrial DC bus protection where you need a compact single-pole device.
The 220 VDC maximum operating voltage is the key spec that differentiates this part. Standard AC-rated MCBs typically top out around 60–72 VDC for a single pole. The 5SL5120-7RC handles 220 VDC across one pole, which means it can directly protect a 220 VDC bus without needing series-connected poles. The C-curve (10–15× In magnetic trip) handles moderate inrush from DC loads like power supplies or contactor coils without nuisance tripping.
At 18 mm width (1 modular unit), it occupies a single slot on a standard DIN rail.