Distribution System Reliability Enhancement Using High-speed Vacuum Circuit Breaker

The electrical distribution system of the Metropolitan Electricity Authority operates at voltage levels of 12kV and 24kV via both underground cables and overhead lines. In certain service areas, a combination of underground main feeders and overhead lateral feeders is used. The circuit breakers at the substations are equipped with the off auto-reclose function to prevent potential damage from faults occurring in the underground feeder cables. Based on recorded statistics, this distribution system frequently experiences prolonged power interruptions in the entire feeder lines when temporary faults occur in the lateral feeders.Therefore, this research aims to overcome such problems by studying and installing high-speed vacuum circuit breakers: reclosing circuit breakers that operate faster than the overcurrent protection relays at the substations. The results of the installation were found to solve the mentioned problem and also reduce the effects of voltage dips.