Objectives: Investigation of insulation to judge the health of the condenser bushing with different techniques has been the area of interest for the researchers in recent past. Power transformers and their bushings are manufactured with oil impregnated paper insulation but their insulation integrity is comprised due to absorbed, residual or liberated moisture/ water which leads to further deterioration and catastrophic failure. Methods: Conventional measurement technique taken at rated power frequency only gives relative indication of specific dielectric properties and health of the condenser bushings. This article introduces a new approach for insulation assessment of the condenser bushings where OIP insulation as a key component has been investigated in a wide frequency response spectrum and to confirm the validity of this approach, measurements were taken on several condenser bushings of same type and age. Findings: The advance technique is a nondestructive method which evaluates the water concentration of the test object. The resulting curve is highly determined by the behavior of solid insulation and it is also sensitive to oil conductivity and insulation geometry of the bushing. Furthermore, the interpretation scheme related to dielectric response is explained. Applications: The signatures achieved helps in reliable data analysis and can be used in qualitative comparisons of bushings which compliments the available quality assurance techniques in the factory. This approach can also be used for frequent monitoring and effective moisture management at site.
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