Upload File

isolacao dielectric chracteristics

19
EVALUATION OF POWER TRANSFORMER INSULATION THROUGH MEASUREMENT OF DIELECTRIC CHARACTERISTICS Victor V. Sokol ov and B oris V. Va nin ZTZ- Serv ice Com pany INTRODUCTION This paper summarizes our experience with the evaluation of the insulation condition and the identification of defects in spaces of the main insulation of power transformers. Specifically, this evaluation is based on the dissipation factor, capacitance and DC insulation resistance measured on core-type large power transformers with oil-barrier insulation systems. The following topics will also be discussed: typical defects in the insulation spaces and their influence on the dielectric characteristics; the effect of water and temperature on the dielectric characteristics of the insulation system; the estimation of the average water content in the pressboard; the evaluation of contamination in the oil spaces and on the insulation surface. Case studies of in-service transformers will be included.  An intelligent assessment of power trans former serviceability requires thoroug h knowledge of the actual condition of the unit. This information is also essential to determine the life-extension program for aging equipment. One of the main life limiting factors is the reduction of the dielectric strength in the spaces of the main insulation, which is caused by an accumulation of moisture and aging contaminants, and a deterioration of insulation due to partial discharge activity. Our experience has shown that about 30% of the large power transformer failures, after 15-20 years of operation, occur due to a breakdown of insulation 1 . There is convincing evidence that the insulation system works as an effective filter which tries to clean the oil from the aging products and water. We have found that a dramatic reduction in the dielectric strength of the oil- barrier insulation system may occur under conditions where the measured characteristics of the oil meet all the traditional criteria. TYPICAL DEFECTS IN SPACES OF MAIN INSULA TION Classification of Defects The following typical defects in the transformer insulation system can be identified:  General moistening of the cellulose insulation. The major part of water is concentrated in the "thin" Insulation, namely the pressboard barriers 2 .  Oil contamination with water, conducting particles and aging products.  Insulation surface contamination due to:  - an adsorption of oil aging products by the su rface o f the solid insulation - a d eposit of inso luble a ging products in area s of high electrical stress 3  - a deposit of conducting particles in areas of high electrical stress 4 . The above defects usually fall into the category of reversible defects. The damage created by partial discharge activities is usually irreversible. This type of damage usually

Upload: -

Post on 04-Jun-2018

215 views

Category:

Documents


0 download

Report

TRANSCRIPT

Page 1: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 1/19

Page 2: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 2/19

Page 3: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 3/19

Page 4: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 4/19

Page 5: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 5/19

Page 6: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 6/19

Page 7: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 7/19

Page 8: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 8/19

Page 9: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 9/19

Page 10: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 10/19

Page 11: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 11/19

Page 12: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 12/19

Page 13: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 13/19

Page 14: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 14/19

Page 15: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 15/19

Page 16: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 16/19

Page 17: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 17/19

Page 18: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 18/19

Page 19: ISOLACAO Dielectric Chracteristics

8/13/2019 ISOLACAO Dielectric Chracteristics

http://slidepdf.com/reader/full/isolacao-dielectric-chracteristics 19/19


NBR 7289 - 2000 - Cabos de Controle Com Isolacao Extrudada de PEou PVC Para Tensoes Ate 1 kV - Requisitos de Desempenho

On the dielectric function tuning of random metal-dielectric

CHRACTERISTICS OF MEASURING INSTRUMENTS by NAVEEN TOKAS

Dielectric (2)

25 Dielectric Properties of Epoxies - John P Kummer Tip 25 - Dielectric...Tip Dielectric Properties of Epoxies 25 Dielectric, by definition, means any insulating medium which intervenes

SHIP CHRACTERISTICS FOR SALVAGE CALCULATIONS III lllf~lffffff · rd-ai51 816 default ship chracteristics for salvage calculations iii i (u) washington consulting group dc c r thompson

THE USE OF DIELECTRIC MIXTURE EQUATIONS TO ANALYZE THE DIELECTRIC

Me Dielectric

Avaliacao Isolacao Bucha Condensiva Ma

Dielectric Elastomers

Dielectric Spectroscopy

SEISMIC STRATIGRAPHY. PROCEDURE 1. IDENTIFY & MAJOR DEPOSITIONAL UNITS 2. INTEGRATE WELL & SEISMIC 3. ANLYZE REFLECTION CHRACTERISTICS 4. RELATE LITHOLOGY

Dielectric Handout

Polymeric Dielectric Materials - InTech - Opencdn.intechopen.com/pdfs/39574/InTech-Polymer_dielectric_materials.pdf · 4 Dielectric Material materials generally have higher dielectric

Dielectric Constant

Dielectric constant (DC value) Compendium · 4 DC compendium Dielectric characteristics The dielectric constant ε The dielectric constant of an insulating material is the result

Wiggin dielectric

Drying Chracteristics

dielectric antennas

Physics Dielectric

Natural Lighting Systems Based on Dielectric …cdn.intechopen.com/pdfs/39575/InTech-Natural_lighting_systems...156 Dielectric Material efficient dielectric prismatic hollow light

A simple calculation of dielectric loss from dielectric dispersion …€¦ ·  · 2012-02-24A Simple Calculation of Dielectric Loss from Dielectric ... relaxation time, ... A simple

Dielectric Properties of Glass Lecture 2: Dielectric in … Vitreous State – The Physical Properties of Glass Dielectric Properties of Glass Lecture 2: Dielectric in an AC Field

Dielectric Measurement

Dielectric Isolation Valve - Grundfosnet.grundfos.com/Appl/ccmsservices/public/literature/... · Dielectric Isolation Valve (Patent Pending) Description The Dielectric Isolation Valve

Dielectric Constants

Fabian Winkler DIELECTRIC - Purdue Universityfwinkler/DIELECTRIC/...Fabian Winkler DIELECTRIC dielectric: The term "dielectric" refers to a substance that is a poor conductor of electricity

Miniaturized dielectric waveguide filterseprints.whiterose.ac.uk/88315/1/Miniaturized Dielectric Waveguide... · This is an author produced version of Miniaturized dielectric waveguide

Dielectric Coat

Dielektrizitätskonstante εr Dielectric Constant Constants.pdf · 2 DIElEKTRIZITÄTSKONSTANTE DIElECTRIC CONSTANT DIElEKTRIZITÄTSKONSTANTE DIElECTRIC CONSTANT Irrtümer und Änderungen

Dielectric Course

Dielectric material options for integrated capacitors … · Dielectric material options for integrated capacitors ... Dielectric Material Options for Integrated Capacitors ... these

Dielectric Soil Moisture Sensors - UC Drought Managementucmanagedrought.ucdavis.edu/PDF/DROUGHT_WEB _DIELECTRIC.pdf · Dielectric Soil Moisture Sensors Dielectric soil moisture sensors

ELECTRICAL AND DIELECTRIC PROPERTIES OF · PDF fileIt shows dielectric constant of 8.1-8.6 and dielectric ... to avoid the effect of moisture. Dielectric ... Electrical and dielectric

dielectric materials