Power Transformers and Corona Testing

There is an increased interest among transformer users in radio influence voltage measurements during routine commercial testing. This paper describes a procedure for determining the presence of corona under oil for transformers. An oscillographic record taken in conjunction with conventional radio influence voltage tests distinguishes between corona in oil which causes progressive deterioration of insulation and corona in air which does not. The data also shows that for high-voltage transformers, the transformer bushing with its capacitance tap provides a suitable coupling capacitor for radio influence voltage tests.

[1]  C. W. Ross,et al.  Considerations in Specifying Corona Tests [includes discussion] , 1956, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[2]  H. S. Dixon.  Rapid determination of corona loss from voltage-charge diagrams , 1959, Transactions of the American Institute of Electrical Engineers, Part I: Communication and Electronics.

[3]  J. B. Whitehead,et al.  Wave form and amplification of corona discharge , 1922, Journal of the American Institute of Electrical Engineers.

[4]  T. W. Dakin,et al.  Effect of electric discharges on the breakdown of solid insulation , 1954, Transactions of the American Institute of Electrical Engineers, Part I: Communication and Electronics.

[5]  J. R. Nye,et al.  Corona Studies - In Relation to Insulation [includes discussion] , 1955, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[6]  F. J. Vogel,et al.  Corona Measurements on Oil-Insulated Transformers , 1957, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[7]  W. A. Keen,et al.  Relationship Between Corona and Radio Influence on Transmission Lines, Laboratory Studies I-Point and Conductor Corona , 1957, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[8]  T. W. Liao,et al.  Detection of Corona in Oil at Very High Voltages [includes discussion] , 1954, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[9]  R. J. Hopkins,et al.  Development of Corona Measurements and Their Relation to the Dielectric Strength of Capacitors , 1951, Transactions of the American Institute of Electrical Engineers.

[10]  J. G. Anderson.  Ultrasonic Detection and Location of Electric Discharges in Insulating Structures [includes discussion] , 1956, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[11]  F. J. Vogel.  Factors influencing the insulation coordination of transformers , 1933, Electrical Engineering.

[12]  T. W. Dakin,et al.  A Capacitance Bridge Method for Measuring Integrated Corona-Charge Transfer and Power Loss per Cycle , 1960, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[13]  J. H. Carpenter,et al.  Ultrasonic Corona Detection in Transformers , 1965 .