Mechanism of functionality of semiconducting materials and reliable anti-corona protection designs of high-voltage generator windings

This paper covers the works, carried out at the Research & Development Department of the plant "Electrotyazhmash" Ukraine, for developing stable and reliable semiconducting materials and anti-corona protection designs for preventing corona discharges and flashovers on the end turns of high voltage stator windings up to 24 kV. The mechanism of the way non-linear resistance on the base of silicon carbide powder works was studied and the principles for obtaining stable properties of such compositions were found. The designs and technology of manufacturing of the end turns anti-corona protection simultaneously with heat treating groundwall insulation were developed and gave the stable and reliable characteristics. The investigation of the state of these systems of anti-corona protection at the power stations after 20-25 years of the operations shows that they have no surface discharges at the operation and standard periodical tests.