Title :
Application of relaxation current measurements to on-site diagnosis of power transformers
Author :
Houhanessian, Vahe Der ; Zaengl, Walter S.
Author_Institution :
High Voltage Lab., Swiss Fed. Inst. of Technol., Zurich, Switzerland
Abstract :
Results of relaxation current measurements on impregnated pressboard samples and on multi-layer arrangements of pressboards in series with oil ducts are presented. The measurements have been performed dependent on the material properties of oil and pressboard and the volume ratio of these materials. Calculated values of related dielectric quantities such as tanδ versus frequency, based on equivalent circuits obtained from relaxation currents are also shown. The relaxation currents of multi-layer test objects are calculated from the dielectric properties of the individual components and their geometrical capacitances. Finally, it is shown that relaxation currents of power transformers can easily be measured and their evolution can be described well by basic relations of linear dielectric theory
Keywords :
ageing; composite insulating materials; dielectric losses; dielectric relaxation; electric current measurement; equivalent circuits; insulation testing; life testing; power transformer insulation; power transformer testing; equivalent circuits; geometrical capacitances; impregnated pressboard samples; linear dielectric theory; multi-layer arrangements; oil ducts; on-site diagnosis; power transformers; relaxation current measurements; tanδ; volume ratio; Current measurement; Dielectric materials; Dielectric measurements; Ducts; Equivalent circuits; Frequency; Material properties; Performance evaluation; Petroleum; Volume measurement;
Conference_Titel :
Electrical Insulation and Dielectric Phenomena, 1997. IEEE 1997 Annual Report., Conference on
Conference_Location :
Minneapolis, MN
Print_ISBN :
0-7803-3851-0
DOI :
10.1109/CEIDP.1997.634555
