Condenser Bushing Core Explained

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Basic Concept and Construction of a Condenser Bushing Core

Condenser bushings may appear simplistic, but they are the product of highly sophisticated design and manufacturing process. Unlike solid bulk bushings, a condenser bushing uses coaxial conducting layers inserted at predetermined radial intervals within the insulation; this construction separates the centre conductor from the external insulator (housing) of the bushing.

Capacitance-Graded Bushing Condenser Core

Capacitance-Graded Bushing Condenser Core

The multiple conductive inserts create concentrically arranged and series-connected capacitive elements called ‘condensers’. Their purpose is to control (grade axially and radially) the electric field around the centre conductor so that the voltage is distributed more uniformly across the bushing’s surrounding insulation system. The electric field is controlled in such a way as to optimise a bushing’s size, mass, and electrical performance characteristics, based upon the voltage class and other duty requirements.

Difference in Electric Field Distribution between A Condenser and Non-Condenser Bushing

Difference in Electric Field Distribution between A Condenser and Non-Condenser Bushing

One end of the condenser chain is connected to the bushing’s central electrode whilst the other is connected to the test tap or voltage tap.

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