DC-rated MCB for 250 V bus protection
The Siemens SENTRON 5SL5204-6CC is a 2-pole DC miniature circuit breaker rated 250 V DC with a B tripping characteristic at 4 A and a breaking capacity of 10 kA. This is a purpose-built DC breaker — the voltage rating is specific to DC circuits, not an AC/DC dual-rated device, so it is the correct choice for a 250 V DC distribution bus or string combiner box rather than a standard AC panelboard. On a 4 A frame that means magnetic trip between 12 A and 20 A — fast enough to clear a hard fault without nuisance tripping on cable charging current.
Mounting position is unrestricted. Touch protection is built in.
