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Description / Abstract:
This guide recommends tests and evaluation procedures, as well
as criteria and methods of maintenance, for natural ester-based
transformer insulating fluids. These base fluids are also known as
vegetable seed oils. Methods of reconditioning natural ester-based
insulating fluids are also described. Where instructions given by
the transformer or fluid manufacturer differ from those given in
this guide, the manufacturer's instructions are to be given
preference.
Purpose
There is growing interest in and usage of natural ester
dielectric coolants for transformer applications. These fluids are
currently being used in the range of small distribution class
transformers to medium power transformers. They are being applied
in new equipment and for retrofilling existing equipment. It is
important that a guide be developed to assist the transformer
operator in maintaining the fluid in serviceable condition. This
guide, therefore, recommends standard tests and evaluation
procedures, methods of reconditioning and reclaiming natural ester
fluids, and the analysis results at which reprocessing becomes
necessary. It will also address the routines for restoring
resistance to oxidation, where desired, by the addition of
inhibitors.