A Complex Permittivity Based Sensor for the Electrical Characterization of High-Voltage Transformer Oils

Abstract

Abstract:This work investigates the use of a specially designed cylindrical metal cell, in order to obtain complex permittivity and tanδ data of highly insulating High Voltage (HV) transformer oil samples. The data are obtained at a wide range of frequencies and operation temperatures to demonstrate the polarization phenomena and the thermally stimulated effects. Such complex permittivity measurements may be utilized as a criterion for the service life prediction of oil field electrical equipment (OFEE). Therefore, by one set of measurements on a small oil volume, data may be provided on the impending termination, or continuation of the transformer oil service life. The oil incorporating cell, attached to the appropriate measuring units, could be described as a complex permittivity sensor. In this work, the acquired dielectric data from a great number of operating distribution network power transformers were correlated to corresponding physicochemical ones to demonstrate the future potential employment of the proposed measuring technique.

Measurement of Complex Dielectric Permittivity in Oils from High-Voltage Transformes Using a Coaxial Probe

“…o Low values of the dielectric constant, and more so those of the loss constant, are of the same order of magnitude as those reported by Dervos in [7]. Low losses agree with that expected of an insulating oil to manage high voltages.…”

“…The values obtained in a VNA of the reflection coefficient are converted into the real and imaginary part of the complex dielectric permittivity by using theoretical models of the cable's open end. In [7] Dervos and Paraskevas show work similar to the work presented herein, but the transformer oil samples are characterized by using a high-cost measurer of RLC parameters; besides, the frequency range analyzed by them goes from 20 Hz to only 1 MHz].…”

A Comprehensive Review of Operation and Control, Maintenance and Lifespan Management, Grid Planning and Design, and Metering in Smart Grids

“…It is necessary a new concept, called Translational Knowledge, which comprises: fault locating, alarm processing, and protective relaying. The improvement of the permittivity in the elements of the electrical system is important, and Dervos et al [9] propose an improvement by means of a cylindrical metal cell.…”

Contribution au développement de nouveaux outils permettant de prolonger la durée de vie des transformateurs de puissance /

“…La réponse fréquentielle du diélectrique a été largement utilisée comme outil de diagnostic pour les systèmes d'isolation papier/huile [22,43,46,48]. Le spectre de mesure est souvent utilisé sur une gamme de fréquences allant de mHz ou moins, jusqu'au kHz ou plus et elle peut parfois atteindre les MHz.…”