ACCELERATED THERMAL AGING OF PAPER INSULATION IN MINERAL OIL RETROFILLED WITH MINERAL OIL, NATURAL ESTER, AND GAS-TO-LIQUID (GTL)
For a long time, mineral oils are preferred as insulating fluid in power transformers due to their availability and low cost. Right now, the number of mineral oil filled transformers that are approaching end of their normal life expectancy is increasing. A proposed method to slowing down the agei...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/74104 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | For a long time, mineral oils are preferred as insulating fluid in power transformers due
to their availability and low cost. Right now, the number of mineral oil filled
transformers that are approaching end of their normal life expectancy is increasing. A
proposed method to slowing down the ageing process and optimize its efficiency is
possible by replacing mineral oil with natural ester. These fluids have additional benefit
such as biodegradable, non-toxic, high fire point and low calorific value whichreduced
fire and environmental risk if the unit fails or when it is decommissioned. Thispaper
reports the effect of replacing mineral oil with different dielectric fluid, on the aging
rate of dried cellulosic materials under air atmospheres. Sealed glass tubes of cooper,
dried Pressboard (PB) and thermally upgraded Kraft Paper (TUK) in Natural Ester
(FR3) and Mineral Oil (MO) were aged at 150 ?C for 1334 hours with 336 hoursintervals
of test. The sealed tube material ratios are consistent with IEEE Standard. Some of the
mineral oil transformer systems were replaced with new MO and FR3 after initial aging
times of 672 hours. Cellulose degradation was determined using degree of
polymerization measurement. The electrical properties of aged fluids were also
measured. Life estimation result show that the aging rate of the cellulose materialis
significantly improved after replacing the MO with FR3. The Natural Ester greater
affinity for moisture, shifts more water from cellulose into the fluid. Hydrolysis
mechanism then consume the water and produce the free fatty acids. These fatty acids
serve as reactants of transesterification that protect the cellulose by strengthening the
ester bonds and forming a barrier for water absorption. These chemical processes proved
by the increase of oil absolute moisture content, the increase of total acidity, and the
decrease of paper moisture content. FTIR spectra of the peak at 1745cm-1
resultincrease
intensity during aging confirms the transesterification reaction has taken place. The
other benefits include the increase fire point up to 250 ?C, the acceptable value of
breakdown voltage and the elimination of oil sludge. |
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