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Adekoya, D. O.
Department of Works and Estate, Federal College of Forestry, Jericho, Ibadan, Oyo State, Nigeria
Adejumobi, I. A.
Department of Electrical and Electronics Engineering, Federal University of Agriculture, Abeokuta, Nigeria
ABSTRACT
The insulating liquids used in liquid-immersed transformers not only provide insulation, but serve to transfer heat from the windings to the surrounding. The liquid must be kept free of contaminants and moisture, just as the air insulation of dry-type transformers. This paper therefore focused on the analysis of the dielectric properties of distribution transformer oil insulation using a case study of installed distribution transformers at Jericho distribution network, Ibadan, Nigeria. Thirty samples were taken from different installed distribution transformers at Jericho distribution network. A conventional dielectric test system (Baur DTA 100 E oil tester) was used to measure the breakdown voltage of these oil samples. A transformer insulating oil passes dielectric test if the measured breakdown voltage is not less than 25kV for 11/0.415kV distribution system or 45kV for 33/0.415kV distribution system in accordance with the guideline from the American Society of testing Materials (ASTM). It was observed that fifteen test samples of transformer insulating oil passed dielectric test while with remaining fifteen samples did not meet up the required standard. This implies that those samples that failed the test would not be able to provide the insulation to the transformer winding which can lead to excessive heat, and consequently might caused explosion or fire outbreak in the transformer.
Keywords: Distribution Transformer, Mineral oil, Breakdown Voltage, Dielectric Strength
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Published
Wednesday, June 21, 2017
Issue
Vol. 3 No. 1, JUNE 2017
Article Section
GENERAL
The contents of the articles are the sole opinion of the author(s) and not of UJET.
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