Insulation Power Factor
Better known as the “DOBLE Test”, IPF or insulation power factor test is the most comprehensive measurement of insulating properties of a power transformer or any apparatus with a winding. Elements such as deterioration, contamination, moisture, and heat can breakdown dielectric strength. Insulation Power Factor Testing measures the dielectric losses due to leakage current thru the insulation.
Winding Resistance Test determines the I2R losses in the transformer, and as a benchmark for assessing possible damages in the field. As a routine test procedure, this procedure is used to determine abnormalities due to loose connections, broken strands of conductors, high contact resistance in tap changers, high voltage leads, and bushings.
The insulation resistance test is a direct current evaluation test of the insulation and gives a reliable indication of the presence of moisture, contamination, or breakdown in the insulation. This test also establishes a benchmark for future comparative tests.