Effect of Surges on Transformer Windings

A study has been made of the reaction of transformer windings in grounded neutral systems when subjected to transient voltage surges such as exist on normally insulated lines. Measurements of the voltage distribution throughout the windings between various elements and to ground were effected by means of a cold cathode type cathode ray oscillograph and sphere spark-gaps. An estimate of the stresses occurring in transformers due to the voltages occurring on transmission systems is made, basing them on the most recent data obtainable. The data indicate that the worst stresses, both within the winding and to ground, are in the vicinity of the line coil.