scholarly journals RECOGNITION OF DISCHARGES THAT ARE ACCOMPANIED BY LOW-TEMPERATURE OVERHEATING BASED ON THE ANALYSIS OF GASES DISSOLVED IN THE OIL OF HIGH-VOLTAGE TRANSFORMERS

2021 ◽  
pp. 20-33
Author(s):  
Oleg Shutenko ◽  
Oleksii Kulyk
Keyword(s):  
Low Temperature ◽  
High Voltage ◽  
Hot Spot ◽  
Gas Analysis ◽  
Test Results ◽  
Dissolved Gas ◽  
Primary Defect ◽  
Combined Defects ◽  
Spot Temperature ◽  
Gas Ratio

Based on the analysis of test results for 135 high-voltage transformers, ranges of gas percentage, gas ratio values were obtained and nomograms for 10 types of combined defects were made, representing discharges with different intensity which are accompanied by overheating with temperature of 150-300°C. It has been established that in transformers with discharges accompanied by low-temperature overheating the values of CH4/H2, C2H2/CH4, C2H2/C2H6 and C2H2/C2H4 ratios determine the discharge energy, in accordance with the norms regulated by the most known standards, the C2H4/C2H6 ratio varies slightly depending on the hot spot temperature and the C2H6/CH4>1 ratio value. Dynamics of defects nomograms changing in the process of their development is analyzed. It is stated by the analysis results that in majority of cases the primary defect is discharges with different intensity, which are accompanied by low-temperature overheating. Overheating occurs in the process of discharge development. The analysis of recognition reliability of discharges with different intensity which are accompanied by 150-300°C overheating was made, using norms and criteria regulated by the most known standards and methods. The results of the analysis show that the most reliable recognition of the defects analyzed is provided to a large extent by the graphical methods, namely the ETRA square and the Duval triangle. The results obtained will significantly increase the recognition reliability of combined defects based on the results of the dissolved gas analysis in the oil.

scholarly journals Analysis of gas composition in oil-filled faulty equipment with acetylene as the key gas

Energetika ◽  
2019 ◽  
Vol 65 (1) ◽  
Author(s):  
Oleg Shutenko
Keyword(s):  
Comparative Analysis ◽  
High Voltage ◽  
Analysis Data ◽  
Gas Analysis ◽  
Identification Accuracy ◽  
Fault Identification ◽  
Gas Composition ◽  
Dissolved Gas ◽  
Dissolved Gas Analysis ◽  
Identification Technique

The article presents results of oil-dissolved gas analysis for 239 units of high-voltage equipment with faults under which acetylene is the key gas. The analysis revealed 13 types of fault with acetylene as the key gas that are differentiated by values of the dissolved gas ratios, their concentrations, and fault nomographs. For each type of fault, graphic domains are plotted that, unlike the nomographs, allow taking into account a possible coordinate drift. A graphic domain based fault identification technique is introduced. The types of fault are briefly described, examples of their identification by different investigators given. Duval Triangle based comparative analysis of the equipment diagnosis data is performed. It is revealed that diagnoses made by different methods may differ significantly both from each other and from actual diagnoses. The results presented allow increasing fault identification accuracy via dissolved gas analysis data.

scholarly journals Diagnostic Simplexes for Dissolved-Gas Analysis

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6459
Author(s):  
James Dukarm ◽  
Zachary Draper ◽  
Tomasz Piotrowski
Keyword(s):  
High Voltage ◽  
Equilateral Triangle ◽  
Gas Analysis ◽  
Two Dimensional ◽  
Unique Combination ◽  
Dissolved Gas ◽  
Dimensional Simplex ◽  
Dissolved Gas Analysis ◽  
Fault Type ◽  
Electrical Apparatus

A Duval triangle is a diagram used for fault type identification in dissolved-gas analysis of oil-filled high-voltage transformers and other electrical apparatus. The proportional concentrations of three fault gases (such as methane, ethylene, and acetylene) are used as coordinates to plot a point in an equilateral triangle and identify the fault zone in which it is located. Each point in the triangle corresponds to a unique combination of gas proportions. Diagnostic pentagons published by Duval and others seek to emulate the triangles while incorporating five fault gases instead of three. Unfortunately the mapping of five gas proportions to a point inside a two-dimensional pentagon is many-to-one; consequently, dissimilar combinations of gas proportions are mapped to the same point in the pentagon, resulting in mis-diagnosis. One solution is to replace the pentagon with a four-dimensional simplex, a direct generalization of the Duval triangle. In a comparison using cases confirmed by inspection, the simplex outperformed three ratio methods, Duval triangle 1, and two pentagons.

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