What is the function of a sectionalizer in a distribution network?

• A. It provides continuous fault protection by tripping on any fault.
• B. It energizes the entire feeder during faults.
• C. It isolates a faulted section after protection operates, helping restore service to unaffected areas.
• D. It regulates voltage on the feeder.

Answer: (C)

Sectionalizers are used to limit the outage area on a distribution feeder by isolating only the faulted section after the upstream protection has operated. In normal operation they stay closed, but when a fault occurs the upstream protective device (like a fuse or recloser) interrupts the fault. Once that protection has opened, the sectionalizer opens the section containing the fault, so the rest of the feeder remains energized and customers in healthy areas can be restored quickly. It doesn’t trip on every fault by itself, it doesn’t energize the feeder during a fault, and it doesn’t regulate voltage.