Technical Article in IEEMA Journal, Jul, 2026 issue: Prevention of Sudden Explosive Failures: Condition Assessment Techniques of OIP & RIP Transformer Bushings
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In this paper, Gautam Nikam and Pramod Rao of Yash Highvoltage review and describe various health monitoring and condition assessment techniques adopted by various users and recommend sequence of tests and evaluation methods.
Transformer bushings are most important and critical components of transformers, and hence, are expected to be highly reliable products. In the event of transformer bushings failure, it usually results in explosive and catastrophic failure of transformers. The effect is downtime of several months of a transformer or reactor accompanied by financial losses, as against the urgency to restore the system at the earliest.
Most bushings in service (for past many years) are bushings with oil impregnated paper (OIP) insulation system. India has commenced largely using resin impregnated paper (RIP) bushings, with a few installations of resin impregnated synthetics (RIS) bushings in Indian grids. OIP bushings are well established up to 800 kV, RIP bushings are now in use up to 420 kV, and RIS bushings are reported to be available up to 245 kV.