Hossein Chalangar - Department of Electrical Engineering Beheshti University Tehran, Iran
Asghar Akbari - Department of Electrical Engineering KNTU University

Failure in bushings always is major factors in transformer failure. In this paper, a Method has been presented for measuring of dissipation factor (PF) and Capacitance (C) which are the most important factors for bushing diagnostic. To achieve this goal, we have defined Least Square (LS) algorithm to compute PF and C by use of Voltage and Leakage current Samples. This algorithm can effectively eliminate frequency fluctuation, noise and other disturbances. Before, LS algorithm, 5 steps Signal processing Levels were applied to Voltage and Leakage current Samples. By use of this method a PF and C Monitoring Device were built and tested on 132 KV bushing. Experimental Results always give Percent of Relative Error in the range of 0.1% and less than it. For checking Robustness of device and algorithm tests were performed 10 times for each sampling frequency and variance of them was calculated.

Condenser Bushing; Diagnostic; Dissipation Factor (DF); Leakage Current; Least Square (LS) algorithm; On-Line Monitoring;