ELECTRONIC SECTIONALIZER CONTROL METHODOLOGY FOR IMPROVED DISTRIBUTION-SYSTEM RELIABILITY

A new methodology for sectionalizer control has been developed that provides more security for applications where system transient currents may cause actuate pickup. Actuate pickup, particularly on ground sensing, may occur during upline ground faults when the sudden load current imbalance is compounded by the unfaulted phase voltage rise causing magnetizing current inrush into a large amount of distribution transformers downline from the sectionalizer. Also, motor backfeed, and non-simultaneous fault clearing may cause actuate pickup if the load is sufficiently large. The control has five automatic restraint features: inrush restraint, count restraint, time-integrated threshold restraint, response restraint, and ground restraint. The last three are new features. The control logic was tested by connecting a prototype to the Transient Network Analyzer and simulating conditions that were suspected of causing problems.