The Effect of Tap Changer Coking and Pitting on Frequency Response Analysis Measurement of Transformer

Frequency response analysis (FRA) method has been proven to detect the transformer winding damage. However, there is no practical study which investigates the damages on transformer tap changer even though it has a high failure rate. Hence, this paper investigates normal and faulty transformer tap changer using FRA. The FRA measurements conducted using four different test configurations. Also, normal tap changer, pitting and coking tap changer contact were investigated. In addition to FRA measurement, winding resistance measurement has been conducted. The transformer turn ratio measurement also conducted to identify the taps positions. This study results significant to understand the effect of pitting and coking tap changer on the transformer frequency response. The results showed that pitting has a slight influence on the frequency response. However, coking shows a huge variation in low-frequency response. This effect observed during the winding resistance measurement.

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Investigation on frequency response analysis measurement method for power transformer impedance

2016 IEEE/PES Transmission and Distribution Conference and Exposition (T&D) ◽

10.1109/tdc.2016.7520036 ◽

2016 ◽

Author(s):

Kohei Ishizaka ◽

Tadashi Koshizuka ◽

Hisatoshi Ikeda ◽

Yasuhiko Taniguchi ◽

Eiichi Haginomori

Keyword(s):

Frequency Response ◽

Measurement Method ◽

Power Transformer ◽

Response Analysis ◽

Frequency Response Analysis ◽

Analysis Measurement

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Application of Frequency Response Analysis Technique to Detect Transformer Tap Changer Faults

Applied Sciences ◽

10.3390/app11073128 ◽

2021 ◽

Vol 11 (7) ◽

pp. 3128

Author(s):

Salem Mgammal Al-Ameri ◽

Abdulaziz Almutairi ◽

Muhammad Saufi Kamarudin ◽

Mohd Fairouz Mohd Yousof ◽

Ahmed Abu-Siada ◽

...

Keyword(s):

Frequency Response ◽

Low Voltage ◽

Experimental Testing ◽

Equivalent Circuit Model ◽

Distribution Networks ◽

Diagnostic Tools ◽

Response Analysis ◽

Frequency Response Analysis ◽

Electrical Transmission ◽

Tap Changer

Power transformers are located in the electrical transmission and distribution networks where different voltage levels are needed. The turn ratio of the low voltage and high voltage windings is mechanically controlled by an on-load tap changer or de-energized tap changer. As the tap changer is the transformer’s only moving part, it is highly susceptible to mechanical failure and aging degradation. While some diagnostic tools have been used to determine the mechanical condition of tap changer contacts, not much attention was given to use the frequency response analysis to diagnose the transformer’s tap changers’ mechanical integrity. This paper is taking one step forward into maturing the application of the frequency response analysis (FRA) technique to detect transformer tap changer faults. In this regard, two common tap changer faults are created, and experimental testing for four FRA test configurations is conducted. For a better understanding of the tap changer fault mechanism, an electrical equivalent circuit model is proposed and designed using Simulink. The simulation and implementation of the equivalent circuits using MATLAB\R2018a.

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