Abstract:
Providing a reliable power supply with minimum breakdowns is one of the main objectives of any
electricity supply company. Frequent breakdowns in the power system occur due to various faults. To
improve network reliability, it is more essential to have a proper analysis of these faults and
incorporate them into the network development plans. The main objective of this research is to do an
analysis of the feeder tripping details in a selected area of the Ceylon Electricity Board Medium
Voltage distribution network. The area of Ratmalana, Kalutara, Mathugama, and Dehiwala which
operates under Western Province South 1, Ceylon Electricity Board were considered for the present
study and feeder tripping data were collected from relevant grid substations for the year 2019. First,
an analysis was done to identify the feeder lines with frequent failures. The Auto type feeder tripping
details of the selected feeders were then further analysed and it was observed 75.02%, 14.48% and
6.15% of faults were due to Earth Faults, Over-Current and simultaneous occurrence of Earth Faults
and Over-Current respectively. The rest were due to the Under Frequency relay operations and 132
kV incoming failures. Auto type feeder tripping occurs repetitively in the network and minimizing
them leads to building up a healthy network. These repetitive failures can be minimized by
addressing solutions for individual feeder lines, where frequent failures occur. Hence a
comprehensive analysis to identify the reasons for auto type feeder trippings is extremely important.
Utilities can incorporate these research findings in their network development plans. They will
consequently be able to eliminate many repetitive breakdowns on the Medium Voltage Network, and
thereby improve the network quality while maintaining reliability indices at an optimal level and
increase their financial revenue.
Keywords: Auto type Feeder tripping; Ceylon Electricity Board; Earth Faults; Medium voltage
distribution network; Over-Current Faults
