Abstract—Bushings are a critical component in electricity transportation. They are used in substation buildings, transformers, locomotives, and switchgear. Bushings cause more than 15% of transformer failures. The main purpose of a bushing is to transfer load currents in and out of metal (grounded) enclosures at system voltages. The insulation system breaks down, causes bushing failure results in tank rupture, violent explosion of the bushing and fire .Clearly, the risk and likelihood of collateral and personnel damage is a major concern in such an eventuality. This research is undertaken to study the insulation system of transformer bushing and in-field measurement of power-factor and capacitance using the Doble M4000 insulation analyzer. The case studies on the two different transformers showed how the trend of moisture and dielectric properties changes with the variation of power factor and capacitance of insulation system.

Index Terms—Insulation system, power transformer,Bushing, power factor, capacitance.

Amit Mehta, R. N. Sharma and Sushil Chauhan are with the Electrical Engineering Department of National Institute of Technology, Hamirpur, Himachal Pradesh, INDIA (mehtaamit5@gmail.com)
S. D. Agnihotri is with HPSEB as S.E. (Production).

Cite: Amit Mehta, R. N. Sharma, Sushil Chauhan and S. D. Agnihotri, "Study the Insulation System of Power Transformer Bushing," International Journal of Computer and Electrical Engineering vol. 3, no. 4, pp. 544-547, 2011.