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Study and Analysis Condition Assessment of Power Transformer OLTC by Duval Triangle Method via IT Support

Juthathip Haema, Rattanakorn Phadungthin



This paper present to study and analysis condition assessment of power transformer OLTC by Duval Triangle
method via IT support. The historical test results of the dissolved gas analysis in the OLTC of power transformers rated
115/22 kV 50 MVA is analyzed as an example. To record the data conveniently and systematically as well as to encounter
less time-consuming for the condition evaluation, IT support is required in this work. The recorded data with the quantity
of combustible gases produced in the insulating oil of OLTC is analyzed by dissolved gas analysis, which is Duval
triangle then applied to specify any faults occurring in the OLTC. Three combustible gases are plotted as a coordinated
point into the triangle that is separated into several zones of specific faults. Finally, the known condition can be used to
plan appropriate maintenance effectively in the utility. This results in higher system reliability and longer useful lifetime
of the OLTC.


Condition evaluation, power transformer, On Load Tap Changer

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