Field experiences with measurements of dielectric response in frequency domain for power transformer diagnostics
Journal article, 2006

Some new methods, based on characterization of the dielectric response of transformer insulation in time and frequency domains, have been pointed out by CIGRE as suitable to assess moisture content in pressboard and paper. Measuring devices available today on the market are quite robust in field conditions; however there is a risk that undesired internal and external factors might influence the measurements. These influences can lead to mistaken interpretation of insulation wetness. Operators should therefore be aware of the risks appearing at different measuring conditions and of the precautions that can be taken to minimize their effects. This work presents a systematic investigation on the influence of some factors on the results of dielectric response measurements in field conditions. The errors that can be committed during the measurements if certain precautions are not taken, with different equipment connected in parallel, are evaluated. The influence of rain and electromagnetic disturbances are also analyzed proposing solutions to attenuate their effects. Finally, a discussion on the influence of temperature distribution follows. The work is concentrated on frequency response measurements, although some results from the use of polarization and depolarization current technique are also discussed. © 2006 IEEE.

Field measurements

water content

frequency domain spectroscopy

transformer diagnostics

oil-paper insulation


Jörgen Blennow

Chalmers, Materials and Manufacturing Technology, High Voltage Engineering

Chandima Ekanayake

Chalmers, Materials and Manufacturing Technology, High Voltage Engineering

Krzysztof Walczak

Poznan University of Technology

Belen Garcia

Universidad Carlos III de Madrid

Stanislaw Gubanski

Chalmers, Materials and Manufacturing Technology, High Voltage Engineering

IEEE Transactions on Power Delivery

0885-8977 (ISSN) 1937-4208 (eISSN)

Vol. 21 2 681-688

Subject Categories

Other Electrical Engineering, Electronic Engineering, Information Engineering



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