Determination of the thermal aging factor for life expectancy of 550 kV transformers with a preventive test

It is feasible to survey actual performances of degradation for 550 kV transformers by a preventive test. By means of condition monitoring, it is possible to forecast the transformers' lifetime. Such data, particularly in an application where few or no failures are expected, can provide considerably more information than the failure-time data from a traditional accelerated life test. In order to develop a life model for 550 kV transformers, the effect of temperature on a thermal aging factor is taken into account since it is associated with various degradation performances of a transformer. With the aid of measurement, the thermal aging factor is analysed by the probability plot and the least-squares fitting of data so that all unknown parameters of the life model are estimated. The method will extrapolate the lifetime of large power transformers from a preventive test in practice.

[1]  T.A. Prevost,et al.  Cellulose insulation in oil-filled power transformers: part II maintaining insulation integrity and life , 2006, IEEE Electrical Insulation Magazine.

[2]  E. Gockenbach,et al.  Component Reliability Modeling of Distribution Systems Based on the Evaluation of Failure Statistics , 2007, IEEE Transactions on Dielectrics and Electrical Insulation.

[3]  I. Hohlein,et al.  Aging of cellulose at transformer service temperatures. Part 1: Influence of type of oil and air on the degree of polymerization of pressboard, dissolved gases, and furanic compounds in oil , 2005, IEEE Electrical Insulation Magazine.

[4]  T. Miyamoto,et al.  Proposals for an improvement in transformer diagnosis using dissolved gas analysis (DGA) , 1995 .

[5]  E. Gockenbach,et al.  Life Management of the Large Power Transformers and the high Voltage SF6 Circuit Breakers , 2010 .

[6]  Gian Carlo Montanari,et al.  Aging phenomenology and modeling , 1993 .

[7]  E. Gockenbach,et al.  Investigations on cavities inside liquid-immersed paper and pressboard insulation materials and their influence on the electrical behavior , 2000, Conference Record of the 2000 IEEE International Symposium on Electrical Insulation (Cat. No.00CH37075).

[9]  Ahmad Gholami,et al.  Insulation Condition Assessment of Power Transformers Using Accelerated Ageing Tests , 2009 .

[10]  Y. Makino,et al.  Absorption of CO/sub 2/ and CO gases and furfural in insulating oil into paper insulation in oil-immersed transformers , 1994, Proceedings of 1994 IEEE International Symposium on Electrical Insulation.

[11]  D. M. Allan.  Practical life-assessment technique for aged transformer insulation , 1993 .

[12]  D. Linhjell,et al.  Aging of oil-impregnated paper in power transformers , 2004, IEEE Transactions on Power Delivery.

[13]  Harry Gumilang.  Unique relationship between interfacial tension test (IFT) and neutral number test (Acidity) of transformer insulation oil in PLN P3B JB - Jakarta and Banten Regional , 2009, 2009 IEEE 9th International Conference on the Properties and Applications of Dielectric Materials.

[14]  Susan Redline,et al.  IEEE Guide for Loading Mineral- Oil-Immersed Transformers and Step-Voltage Regulators , 2012 .

[15]  P.L. Lewin,et al.  An experiment to evaluate the benefits of processing aged transformer oil , 2006, Conference Record of the 2006 IEEE International Symposium on Electrical Insulation.

[16]  M.K. Pradhan,et al.  Assessment of the status of insulation during thermal stress accelerated experiments on transformer prototypes , 2006, IEEE Transactions on Dielectrics and Electrical Insulation.

[17]  Thomas W. Dakin,et al.  Electrical Insulation Deterioration Treated as a Chemical Rate Phenomenon , 1948, Transactions of the American Institute of Electrical Engineers.