Monitoring the quality of insulation during aging of distribution transformers.

摘要

One of the biggest problems faced by the power industry today is the age of the infrastructure. Many of the elements of the system are either close to or past there recommended useful life. One of the most important and prevalent elements of the power system are distribution transformers. In the past, most of the distribution transformers were replaced on a time of usage basis. For example, if a transformer is rated for thirty years of life, they have traditionally been replaced within that time frame. But, transformers are not loaded at 100% of the rated capacity at all times. So, the useful life of the transformer could be much longer than its rated life. Hence, there has been a shift from time based replacement to condition based replacement.;During this research work, two 7.2 kV, 10 kVA distribution transformers were subjected to an accelerated aging process. During the aging process, breaks were taken to measure the quality of the transformers, which is determined by the quality of the insulation. Several classical methods of determining insulation quality, such as insulation resistance, polarization index, dielectric discharge, step voltage, and furanic analysis, were performed on the transformers. In addition, two different tests which are relatively new were performed IDAX testing and PDC testing. The research work was based on validating the newly developed testing methods using results of classical diagnostics. A close correlation between the two tests was obtained with a maximum error of 2:1.