High-Voltage Equipment Insulation Oils Moisture Content Evaluation Using the Method of Gas Chromatography Under Various Temperature Conditions

摘要

Liquid insulation moisture content control is essential because liquid in “oil-cellulose” insulation system is present in several forms (bonded, dissolved, emulsive and layered). In case of load change, therefore, temperature drop water can migrate from one form into another, and, yet worse, diffuse towards solid insulation, be adsorbed and decrease tolerance to short-circuit current exposure. Emulsive water in dielectric liquid is especially dangerous as it considerably decreases electrophysical characteristics of internal insulation system of high-voltage equipment. With the purpose of timely location of dangerous condition of internal insulation it is important to know general moisture content in dielectric liquid in practice. At present out of all known methods of moisture evaluation in insulation liquids only two allow to measure total moisture concentration based on coulometric titration and gas chromatography. In the process of high-voltage equipment operation oil complex chemical content changes significantly. New compounds interfering evaluation of the target component - water, appear in oil. That's why using moisture analysis methods in old oxydized oils, optimization of technological operations realization allowing to obtain the most reliable result is very important. The present article shows results of a research of different oil brands dehydrating on different chromatography modes. Comparing data of chromatographic analysis with the results of moisture analysis obtained using Karl Fischer method; satisfactory recovery rate at evaporator temperature mode of 240-300°C can be noted.