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Page 149

| Oil-Filled Bushings |

| For breakers operating at greater voltages (to about 75,000 V), the conductor may be mounted inside porcelain cylindrical insulators filled with oil. The oil space may be divided by thin insulating cylinders of special materials, including plastics (for example, herkolite), with an oil gauge at the top to indicate the level of oil in the bushing. The insulation of these bushings is dependent on the oil, which has high insulating qualities and helps keep the bushing cool. These bushings are similar to those for transformers. See Fig. 2-18. |

| Condenser Bushings |

| For even higher voltages (usually over 75,000 V), conductors may be insulated with layers of oil-impregnated special paper, with metal foil inserted at several locations among the layers (Fig. 8-20). The layers of insulation at the |

Figure 8-20
Condenser bushing
for oil circuit
breaker. (Courtesy,
Westinghouse
Electric Co.)

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