IDENTIFICATION OF TECHNOLOGICAL DEFECTS IN HIGH-VOLTAGE SOLID INSULATION OF ELECTRICAL INSULATION STRUCTURES ON THE CHARACTERISTICS OF PARTIAL DISCHARGES

Abstract

Introduction. High-voltage insulation systems always have some background level of the partial discharges, which does not have any significant effect on the life of the electrical insulation design. At the same time, partial discharges destroy high-voltage insulation, leading to a carburization zone around the defect. This is the «hidden» period of development of the defect. The development of a defect zone, sooner or later, leads to an arc breakdown of the entire insulating gap. Purpose. The substantiation of the efficiency of detection of technological defects in high-voltage solid insulation of electrical insulating structures according to the characteristics of partial discharges. Methodology. The conditions for the occurrence of partial discharges in the thickness of the polymer insulation are considered. The possible values of the voltage of the beginning of partial discharges are determined for a model of a cylindrical air gap near the conductor of a power cable. It is shown that with the same applied voltages to high-voltage insulation, in the latter case, air inclusions of smaller thickness are activated in comparison with a flat structure. Practical value. The efficiency of detection of technological defects in solid composite case insulation of the stator winding of turbo- and hydrogenerators is shown. Based on the comparison of the amplitude of the pulses of partial discharges of positive and negative polarity, the estimated location of the technological defects in the insulation has been established.

Keywords

• technological defects
• partial discharges
• voltage of the start of partial discharges
• glass-mica paper tape
• amplitude of pulses of partial discharges
• location of the defect