10 Bushing Test
In this chapter, information regarding bushing power factor/ tan δ measurement is provided.
According to IEEE C57.152-2013 standard, generally bushings are classified by design as:
• Condenser type
◦ Insulating liquid-impregnated paper insulation, with interspersed conducting
(condenser) layers or insulating liquid-impregnated paper insulation, continuously
wound with interleaved lined paper layers
◦ Resin-bonded
◦ Resin-impregnated paper insulation, with interspersed conducting (condenser) layers
• Non-condenser type
◦ Solid core or alternate layers of solid and liquid insulation
◦ Solid mass of homogeneous insulating material (e.g., solid porcelain)
◦ Gas filled
Condenser type bushing includes a series of concentric capacitors from centre conductor to
ground. Some types also include a tap electrode near the ground flange. In the picture below, a
schematic of high voltage bushing can be seen.
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