<?xml version="1.0" encoding="UTF-8"?> <article key="pdf/4707" mdate="2013-06-26 00:00:00"> <author>E. A. Feilat and I. A. Metwally and S. Al-Matri and A. S. Al-Abri</author> <title>Analysis of the Root Causes of Transformer Bushing Failures</title> <pages>791 - 796</pages> <year>2013</year> <volume>7</volume> <number>6</number> <journal>International Journal of Electrical and Computer Engineering</journal> <ee>https://publications.waset.org/pdf/4707</ee> <url>https://publications.waset.org/vol/78</url> <publisher>World Academy of Science, Engineering and Technology</publisher> <abstract>This paper presents the results of a comprehensive investigation of five blackouts that occurred on 28 August to 8 September 2011 due to bushing failures of the 13233 kV, 125 MVA transformers at JBB Ali Grid station. The investigation aims to explore the root causes of the bushing failures and come up with recommendations that help in rectifying the problem and avoiding the reoccurrence of similar type of incidents. The incident reports about the failed bushings and the SCADA reports at this grid station were examined and analyzed. Moreover, comprehensive power quality field measurements at ten 3311 kV substations (SSs) in JBB Ali area were conducted, and frequency scans were performed to verify any harmonic resonance frequencies due to power factor correction capacitors. Furthermore, the daily operations of the onload tap changers (OLTCs) of both the 125 MVA and 20 MVA transformers at JBB Ali Grid station have been analyzed. The investigation showed that the five bushing failures were due to a local problem, i.e. internal degradation of the bushing insulation. This has been confirmed by analyzing the time interval between successive OLTC operations of the faulty grid transformers. It was also found that monitoring the number of OLTC operations can help in predicting bushing failure.</abstract> <index>Open Science Index 78, 2013</index> </article>