Internal discharges and electric treeing

The maximum voltage which can be applied to the specimen without a discharge in the cavity is then, taking eg = 1, given by 

The gas discharge process will continue to drive the growth of the tree until the tree structure joins the electrodes. Large destructive currents can then flow, and complete breakdown of the insulation will ensue. 

There are various ways of inhibiting tree growth so as to improve the ability of the material to withstand higher voltages, notably reducing the incidence of voids within the material and/or filling interstices with an insulating liquid. 

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