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How to accurately measure the insulation resistance of an insulator?

Publish Time: 2024-11-05
Preparation before measurement

Before measuring the insulation resistance of an insulator, make sure that the surface of the insulator is clean and dry. Because impurities such as dirt and moisture may form a conductive path on the surface of the insulator, affecting the accuracy of the measurement results. For insulators operating outdoors, use a clean cloth or a special cleaning tool to remove surface dust, oil, etc. At the same time, choose a suitable insulation resistance meter, and its voltage level should be determined according to the rated voltage of the insulator. Generally, for high-voltage insulators, an insulation resistance meter with a higher voltage range, such as a 2500V or 5000V insulation resistance meter, is required.

Measurement method

During measurement, connect the "L" end (line end) of the insulation resistance meter to the high-voltage end of the insulator, and the "E" end (ground end) is reliably grounded. For multi-component insulators, such as an insulation structure composed of multiple insulator strings, a segmented measurement method can be used. First measure the insulation resistance of the entire string of insulators, and then measure each insulator or each group of insulators separately. During the measurement process, the handle of the insulation resistance meter should be shaken at a constant speed, and the speed should be kept stable, usually 120r/min, so that the insulation resistance meter outputs a stable voltage.

Judgement of measurement results

After the measurement is completed, read the reading of the insulation resistance meter. For new insulators, their insulation resistance values should meet the higher values specified in relevant standards. For example, the insulation resistance of new high-voltage porcelain insulators should generally be above several thousand megohms. For operating insulators, if the insulation resistance value drops significantly, such as below the specified minimum value, it may indicate that the insulator has problems such as aging, moisture or local damage. However, it should be noted that the measurement results will be affected by environmental factors (such as temperature and humidity), and these factors should be considered comprehensively when analyzing the results. When the measurement results are abnormal, the measurement can be repeated several times to ensure the accuracy of the measurement, and the insulation performance of the insulator can be further judged in combination with the operating status and appearance inspection of the insulator. By accurately measuring the insulation resistance of the insulator, potential insulation faults can be discovered in a timely manner to ensure the safe and stable operation of the power system.
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