• ETT Level 2.16: Insulating Liquids

    Learn how to recognize and sample different transformer insulating and cooling mediums.

    1. Properties, types, and sampling procedures - Recognize the different insulating and cooling mediums and uses. Have the ability to perform correct sampling procedures.
      • Transformer Oil Basics Transformer oil or insulating oil is an oil that is stable at high temperatures and has excellent electrical insulating properties. It is used in oil-filled transformers, some types of high voltage capacitors, fluorescent lamp ballasts, and some types of high voltage switches and circuit breakers. Its functions are to insulate, suppress corona and arcing, and to serve as a coolant.
      • Sampling Transformer Oils — How and Why to Take a Good Sample [PDF] The results obtained from the analysis of an insulating oil sample can provide unparalleled information concerning the condition of the insulating materials with in electrical apparatus, life as sess ment, and the op er at ing con di tion of the device.
      • Sampling Transformer Oils — Retrieving the Actual Sample [PDF] Different dielectric liquids require sampling from different locations based on their relative density (specific gravity). In general, dielectric liquids with a relative density less than one should be sampled from the bottom drain valve whereas dielectric liquids with a relative density greater than one should be sampled from the top fill valve as long as it is below the liquid level.

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