Achievement of polarization and depolarization current tests for condition estimation of oil-paper insulation using LabVIEW

The polarization and depolarization current (PDC) test is effective to estimate the aging condition of transformer oil-paper insulation. However, the commercial product based on PDC technique is seldom developed currently, and the only product is very expensive and less flexible in application. To investigate the impact of aging condition of oil-paper insulation on its polarization and depolarization current, the PDC test instrument is developed with a computer, a GPIB card and a Keithley 6517 A high resistance electrometer. The required software is built under LabVIEW environment to control this hardware system. The measurement principle, hardware structure and software designing of the instrument are introduced. The PDC is tested on the oil-paper insulation sample by a developed instrument, and the performance between the instrument and a commercial PDC analyzer is comparatively investigated. The results show that the developed instrument operates normally and easily which is sensitive to the aging condition of oil-paper insulation and satisfying enough for PDC tests.