Electric field intensity equaliser for transformer protection - has spiral wound electrodes, within insulating space of transformer, in which equalising potentials are induced by magnetic flux

摘要

Helical layers are wound and connected to transformer windings to obtain an electrical screening effect. This causes the electric fields in an insulating dielectric separating the main windings to be more uniform. The screening layers are wound in the same sense as their respective windings such as to re- distribute the dielectric field intensity by magnetic induction. The helical layers may be of an overlapping foil construction to increase inter-turn capacitance. Field non- uniformities at the ends of the coils may be minimised by including a laminated magnetic screening cap over the end of the inner winding. The system protects the transformer from high voltages surges caused e.g. by lightning.