ET online
November 2007
Measuring Oil

Measuring Oil

02 November 2007

George Robertson - GRScentific

... for measuring moisture in insulating oils.
Moisture in insulating oil not only reduces the efficiency of the oil as an insulator but may also be used to detect signs of degradation in the solid insulation in transformers and switchgear since water is a by-product of the breakdown of this type of insulation. However, oil degrades in the light and over time, and water content should be measured at or near the normal operating temperature of the oil. It is now recognised that inaccuracies can occur when oil is sent to a central laboratory or workshop for breakdown and water content analysis. Local testing allows decisions to be made there and then reducing the danger of putting the equipment back into service with inadequate oil whilst waiting for results to come through from a central laboratory.

Designed to detect the moisture content of insulating oils, primarily within oil-filled transformers and switchgear, Megger has recently launched the KF-LAB oil test set. This fully portable, battery and mains powered unit, can be used on-site or in the laboratory / workshop. The KF-LAB uses Karl Fischer coulometric titrimetry, the recognised industry standard method for determining moisture content, and the standard against which other instruments are calibrated. This method is specifically sensitive to water in samples, and although most insulating oils have water content down in the low mg/kg (ppm) levels, the unit can be used for a much wider range if necessary. The simple to operate KF-LAB has been designed for use by non-laboratory personnel and can provide oil sample results in less than one minute. The results are displayed and printed out in mg/kg water (ppm) complete with time and date of analysis.

Although most Karl Fischer titrators are normally used in a laboratory or workshop, there are occasions when it is advantageous to take the test unit on-site. The KF-LAB is supplied complete with a sturdy carry case, built-in battery power and glassware which has been specifically designed for outdoor use. The KF-LAB can be transported, with the glassware already assembled, ready for immediate use on arrival at the destination. Power cords, sampling syringes, etc, can all be stored in the carry case lid which has a special compartment for this purpose.

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