Liquid Power Factor (PF)
Standard Test Method for Dissipation Factor (or Power Factor) and Relative Permittivity (Dielectric Constant), ASTM D924
Dissipation Factor, or Liquid Power Factor, is a measure of the dielectric losses in an insulating liquid when used in an alternating current electric field. Dissipation factor and liquid power factor are not exactly equivalent, but vary by less than one part in a thousand up to a value of approximately 5% for the liquid power factor. They are essentially interchangeable for the values that are likely to be encountered in operating electrical equipment. Liquid power factor is an electrical property of the oil, and relates both to the function of the oil and to its purity. Highly refined oil, free from contamination, has a very low liquid power factor. Moisture, oxidation, and contamination all serve to increase the liquid power factor. For new oil as received from a supplier, typical specification values for liquid power factor are ≤ 0.050% when measured at 25° C and 0.30% when measured at 100° C. Liquid power factor is a particularly useful in-service tool for testing and monitoring oil because the test is sensitive to moisture, oxidation of the oil, and contamination from outside sources. Frequently, the pattern of increase for the 25° C and 100° C values can be used to identify specific conditions of concern.
Dissipation Factor, or Liquid Power Factor, is a measure of the dielectric losses in an insulating liquid when used in an alternating current electric field. Dissipation factor and liquid power factor are not exactly equivalent, but vary by less than one part in a thousand up to a value of approximately 5% for the liquid power factor. They are essentially interchangeable for the values that are likely to be encountered in operating electrical equipment. Liquid power factor is an electrical property of the oil, and relates both to the function of the oil and to its purity. Highly refined oil, free from contamination, has a very low liquid power factor. Moisture, oxidation, and contamination all serve to increase the liquid power factor. For new oil as received from a supplier, typical specification values for liquid power factor are ≤ 0.050% when measured at 25° C and 0.30% when measured at 100° C. Liquid power factor is a particularly useful in-service tool for testing and monitoring oil because the test is sensitive to moisture, oxidation of the oil, and contamination from outside sources. Frequently, the pattern of increase for the 25° C and 100° C values can be used to identify specific conditions of concern.