Analysis of false tripping for power transformers in Egypt

Abstract

Frequent forced outages of power transformers can significantly affect the performance of industrial and commercial power systems and the processes they control. This paper presents the results of an extensive survey on false tripping of protection devices and systems for power transformers in Egypt. The outcomes of this work are beneficial in improving the design and maintenance of these protection systems to increase the reliability and availability of power systems. The data are obtained from the Egyptian Electricity Transmission Company (EETC). The collected data are in the form of transformer outage reports for eight years, from 2002 to 2009, where the average number of transformers is 1922 in voltage populations ranging from 33 kV to 500 kV and MVA rating from 5 MVA to 500 MVA. Results show that the fire-fighting systems are responsible for the highest number of false trips in all voltage sub-populations except the 220 kV sub-population where the dominant cause of false trips is the bus bar protection.