Outdoor Three-Phase Automatic Medium Voltage Sectionalizer

A sectionalizer is an automatic switching device used in medium-voltage distribution networks to isolate faulty sections of a feeder. Unlike circuit breakers or reclosers, a sectionalizer: does not interrupt fault current. Its main function is to work in coordination with an upstream protective device such as a recloser or circuit breaker. The sectionalizer monitors the line current and counts the number of upstream interruptions during a fault. The typical operating sequence is: A fault occurs on the feeder. The upstream recloser or circuit breaker trips and recloses several times. The sectionalizer counts these interruptions. When the preset count is reached, the sectionalizer identifies that the fault is located downstream. During the next de-energized interval, the sectionalizer opens and isolates the faulty section. After that, when the upstream device recloses, only the healthy part of the network is re-energized.