Protection and Switching: Railroading Electricity

Circuit breakers are used to open and close circuits. They can be operated manually to perform maintenance or will automatically trip if a short circuit occurs. This function in the power system is similar to that of the fuses or breakers in a household distribution panel.

Disconnect switches are found in several locations at a substation. They play a vital role in ensuring worker safety since they electrically isolate circuits or units undergoing maintenance and make this isolation visible. To visualize how a disconnect switch works, just imagine a section of railway track that can be freely lifted and turned to prevent energy from traveling along a path. A disconnect switch is used once a breaker has opened a circuit and no charge is present.

Busbar assemblies are large, generally rigid aluminum conductors that link circuits together. They can be compared to the distribution panel in a home, where electric current arrives. The distribution panel is used to parcel out current among the various circuits to be supplied. The main difference is that busbars carry and distribute very large currents.