CP TD1 Reference Manual V 1.44
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C2 insulation of the bushing. In addition, this tap is sometimes used for
monitoring the partial discharge during factory tests and insulation leakage
current (including partial discharge) during field service operation.
See Figure 12-3 for condenser design and test tap details.
Figure 12-3 Design/construction details of a typical condenser bushing
rated 69 kV and below
12.5.4 Factors Affecting C1, C2 Capacitance and Power Factor
Measurements
As mentioned earlier, the C1 and C2 capacitance of condenser bushings rated
115 kV and above are strictly controlled by design and are mainly dependent
upon oil impregnated, paper insulation. Therefore, the power factor and
capacitance test values under normal circumstances, are not affected too much
by external factors. However, under conditions of contamination and high
humidity, these measurements may be significantly affected. In addition,
capacitively coupled resistive paths to ground may affect these measurements.
These may include supporting structures, wooden crates that are moist/wet,
resistance between bushing mounting flange and the transformer tank, stray
effect from other objects, and external connections during testing. Although, the
Voltage Equalizers
C1 Layer/Foil
Mounting Flange
Oil Impregnated Paper
Central Conductor
Test Tap Spring
Bushing oil/paper in C2 insulation
C1
C2
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