In addition, a greater vulnerability in an OIP transformer bushing type exists to lightning strikes or other factors that can trigger explosive failure.
Additionally, excessive filling of oil reservoirs in horizontal mount applications can lead to severe operational problems.
Unusually high operating temperatures on an OIP bushing can comprise its bushing life and again lead to severe operational problems.
However,the OIP bushing is cheaper than the RIP bushing,so many customers are more likely to choose OIP bushing.
The figure shows the cross-sectional view of OIP Bushing.
In OIP bushing the core is wound from paper and subsequently treated and impregnated with an insulating liquid, generally transformer oil.
The core is contained in an insulating envelope (generally “Porcelain”), the space between the core and the insulating envelope being filled with the same insulating liquid as that used for impregnation.
Bushings are also provided with Oil level gauge & Test Tap. In the center stem is provided which connects the Overhead conductor to transformer winding, this is usually made of copper.
Resin Impregnated Paper (RIP) Bushing
RIP (resin impregnated paper ) consists of a revolutionary new class of insulating material with superior thermal and electrical performance .
The Figure shows the cross-sectional view of RIP Bushing.
In resin impregnated paper (RIP) transformer bushing type the major insulation consists of a core wound from paper and subsequently impregnated with epoxy resin. The casting and curing of this insulation is a carefully controlled process.
A resin-impregnated paper bushing can be provided with an insulating envelope (generally “Silicone Composite insulator”), in which case the intervening space can be filled with an insulating liquid or another insulating medium like polyurethane foam, gel, etc.
Based on the above, it can be said that the major difference between Resin Impregnated Paper (RIP) bushing technology and Oil Impregnated Paper (OIP) bushings is that in OIP technology the condenser cores are impregnated with transformer grade mineral oil that remains in a liquid phase throughout its entire life whereas in RIP bushings the impregnation is carried out via a curable epoxy resin to form a solid condenser.
