Hot Collar Testing
Hot collar testing is one of the methods of measuring the Insulation Power Factor (IPF) of porcelain bushings like main transformer bushing and current transformer bushing. It is performed by literally wrapping or collaring the porcelain insulator by a flexible wire conductor. The conductor is then energized to measure the power factor; for the case in the above picture, the voltage applied was 10 kV for this 230 kV bushing. IPF measurements are usually taken in the top, middle and bottom of the bushing.
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