Measuring Alcohols to Determine Early Stages of Cellulosic Insulation Degradation
National Grid Electricity System Operator
National Grid TO Innovation Team
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Innovation Funding Incentive
Gas Distribution Networks
When cellulose chains that form paper insulation in transformers degrade they
are known to produce a class of compounds called furfurals and this has been
used an indicator of paper ageing for many years. However, the excellent
correlation that is typically seen in laboratory studies between concentration of
Furfurals (FFA) and reduced degree of polymerisation; an indicator of paper
condition, is not usually seen in transformers as they age. The presence of FFA
at relatively high concentrations (>1.5ppm), especially evidence of an increasing
trend in concentration, is a good indicator that the paper is nearing end of life.
When FFA is present at lower levels, or it is apparently stable, then the link to
ageing is less clear.
This project will look at the potential for identifying the early stages of insulating
paper degradation by measurement of methanol and ethanol in oil. Earlier
detection of cellulose breakdown will provide greater visibility of transformers
that are ageing but not in danger of imminent failure and would improve longer
term transformer replacement plans. It might also be possible to identify thermal
design issues during heat run tests of new transformers.