What is the primary purpose of a sectionalizer in a distribution network?

• A. It energizes all sections when a fault occurs.
• B. It provides long-term voltage stabilization.
• C. It isolates a faulted section after protection operates, enabling restoration to unaffected areas.
• D. It regulates frequency on the feeder.

Answer: (C)

The main idea is to limit outage impact by isolating only the faulty portion of the feeder after protection has acted. A sectionalizer doesn’t detect faults by itself; it relies on the status or signals from upstream protection (like a recloser or fuse). When a fault occurs, the upstream protection trips or recloses as needed to clear the fault. The sectionalizer then opens to isolate the specific section that experienced the fault, so the rest of the feeder stays energized and can be restored quickly. It’s about selective isolation of the faulted segment to keep unaffected areas live, not about stabilizing voltage or regulating frequency, or energizing all sections.