DETECTION OF PAPER DEGRADATION

Detection of Paper Degradation in Large Power Transformers

TABLE OF CONTENTS

Introduction3

Technique For Sensing Paper Degradation3

Chemistry Of Cellulose And Methods Of Study Its Degradation4

Data of Paper5

Degree of Polymerization6

High-performance liquid chromatography6

Gas chromatography-mass spectrometry7

Fourier transform infrared spectroscopy8

Paper9

Detection Of Paper Degradation In Large Power Transformers10

Methodology12

Method for determination of 2-furfural and related compounds13

Indication Of Challenges And Future Trends14

Detection of Paper Degradation in Large Power Transformers

Introduction

The paper naturally present in the composition of elements in aging, decay and contribute to the weakening of the works. The paper consists essentially of cellulose fibers. The natural aging process breaks the molecules forming the paper fibers in a slow and irreversible.

The degree and rate of deterioration depends on a part of the chemical instability of the constituent materials and other external factors such as environmental degradation, conditions of storage and handling. Initially, linen rags, hemp and cotton were recycled to make paper.

The mid-nineteenth century, the use of wood fiber resulted in a significant decrease in the quality of the paper. These papers contain more impurities and fibers are much shorter than before. This results in greater fragility and poorer retention over time. The new sizing process with alum and rosin, and the use of certain chemicals to bleach pulp are also responsible for this instability.

Technique For Sensing Paper Degradation

The concentration of furfural (2FAL) dissolved in oil, analyzed by High Pressure Liquid Chromatography and High Resolution (HPLC), although with some limitations, has been successfully used in the diagnosis of the state of degradation of the paper insulation Kraft, the transformers and its monitoring over time. However, the 2FAL dissolved in the oil has a lower sensitivity for detection of degradation of paper "Thermally upgraded" in relation to the Kraft paper.

The knowledge of this fact is of great significance, since the use of paper "Thermally upgraded" current starts to grow, especially in high voltage transformers, which typically operate at higher temperatures.

Are presented phenomena of degradation of paper "Thermally upgraded", which allow to understand the reasons for which the concentration of 2FAL dissolved in oil, it appears to be suitable as an indicator for determining the state of aging of the paper type, as it is for kraft paper, especially as regards the detection of the early stages of degradation of the paper, simultaneously presenting the results of a comparative experimental study of the thermal aging of these two types of paper.

It is very likely that instead of 2FAL, other products produced by degradation of paper, for example furfuryl alcohol, (2FOL), can be used as an alternative indicator of the level of degradation of paper "Thermally upgraded". However, more studies are needed to confirm this hypothesis.

Chemistry Of Cellulose And Methods Of Study Its Degradation

Like all materials, the card is intended to degrade under the action of the time, the use and environmental conservation. To avoid losing, perhaps forever, a cultural heritage of inestimable value, program prudent actions to take to enjoy the good cultural eral, even if ...