DC Circuit Breaker
A protective device that opens on overcurrent and can be reset manually or automatically. Unlike a fuse, it is not a consumable and can also be used as an isolating switch. Its response time is generally longer than a fuse's, so short-circuit protection should be considered separately.
Low-voltage DC systems mostly use the thermal type: the current heats a bimetal strip, which bends and opens the contact. This thermal behaviour naturally tolerates the brief surges of motor start-up and reduces nuisance tripping.
Points to consider when choosing one:
- DC compatibility: do not use a breaker designed for AC in a DC circuit. With direct current the arc does not extinguish by itself, and the breaking capacity is specified separately.
- Voltage rating: the label should clearly state 12 V, 24 V or 48 V DC.
- Reset type: self-resetting types can re-engage again and again before the cause is fixed and stress the system; manually reset types are preferred in assemblies that require maintenance.
A breaker that trips often does not hide the fault, it reveals it. Measure the current under load and look for causes such as mechanical binding, commutator contamination or seized bearings.
Context where this term is used: DC Motor Driver Selection Guide