Condition Assessment of HV Bushings with Solid Insulation based on the SVM and the FDS Methods

Jan Subocz,Marek Zenker,Andrzej Mrozik,Patryk Bohatyrewicz

doi:10.3390/en13040853

Jan Subocz, Marek Zenker + Show 2 more

Open Access

https://doi.org/10.3390/en13040853

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Journal: Energies	Publication Date: Feb 15, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: West Pomeranian University of Technology

Abstract

This paper presents the dielectric response of the insulation of bushings as an effect of the simulated long-term aging process. The experiment was conducted under a condition of a high temperature difference between the current circuit and the cover. The dielectric response was measured with the FDS (Frequency Dielectric Spectroscopy) and the SVM (Step Voltage Measurement) methods. The research has shown the correlation between the aging time and some parameters obtained with the FDS and SVM analysis.

Highlights

Transformer bushings belong to the basic equipment of each high voltage power transformer
The policy of the distribution companies is aimed at lengthening the transformers operating time above the designed lifetime i.e., 30 years what results in arising the situations in which there is big a group of transformers with factory-installed transformer bushings [1,2]
In spite of positive results of the measurements of the dielectric loss factor tgδ measured in mains frequency the bushings installed in such units have the signs of beginnings of the aging processes which are noticeable in the low frequency range 0.01–0.001 Hz

Summary

Introduction

Transformer bushings belong to the basic equipment of each high voltage power transformer. The new use of the SVM method applied mainly in HV motor insulation diagnostics, according to the authors, allows for diagnostics of the most exposed to aging layers and such possibility results from a different distribution of the electric field constant in relation to the alternating field [8]. The aging processes in such composites are caused by the superposition of the action of the electric field, temperature and mechanical stress [11]. M—the coefficient of mechanical durability (MEC), L0 , M0 correspond to Equation (1) The action of these factors in the initial stage of the aging processes primarily causes the occurrence of microdefects in the composite structure.

Test Subject and Research Methodology

The in combined

Impact

The chart ofdeinstallation

Conclusions