Using contactless methods of diagnostics of high electric fields

Abstract

In the electric power industry of Russia and abroad, special attention is paid to the problem of an increase in the number of accidents caused by damage to high-voltage insulators in high-voltage equipment. An analysis of emergencies at substations and open switchgears [1- 2, 4] was carried out, which showed that in most cases the causes of damage to high-voltage insulators are natural aging in an applied electric field, overvoltage, and the presence of initial defects in the manufacture of high-voltage insulators. Based on this fact, we developed various methods of non-contact diagnostics of high-voltage insulators in order to identify defects at an early stage of their development. Particular attention was paid to the method of partial discharges because the characteristics of partial discharges provide information on the parameters of defects. The article describes a set of non-contact methods for remote diagnostics of high-voltage insulators; a two-channel method for remote diagnostics of the operating state of high-voltage insulators, based on the registration of partial discharges by electromagnetic and acoustic sensors; a device that allows visual inspection and the search for faulty high-voltage equipment; remote non-contact method for recording electric fields of high tension of industrial frequency, as well as their spatial orientation based on the electro-optical effect. We developed a mock-up of a portable diagnostic device for implementing research methods for high-voltage dielectric elements to diagnose their technical condition using the described complex of non-contact methods. The measuring device as part of a portable diagnostic device consists of a set of sensors for collecting diagnostic information detected by electromagnetic, acoustic and electro-optical sensors and a voltage phase signal applied to the studied highvoltage insulator. The simultaneous use of several sensors at once made it possible to increase the accuracy of localization of partial discharges in high-voltage insulators. Visualization of diagnostic results is possible at the control room in the form of amplitude-phase, frequencyphase and amplitude-frequency diagrams of the distribution of characteristics of partial discharges and on a portable device in the form of radiation intensity from the selected sensor. A portable diagnostic device made it possible in laboratory conditions to study electrophysical processes in various dielectric materials and products under the influence of strong alternating electric fields. A study was made of the features of defects on the rod and the terminal-terminal contact, a diagram of the electrophysical processes accompanying the emission of partial discharges was constructed, and the causes of their occurrence were established.

Keywords

• remote diagnosis
• partial discharges
• nondestructive testing
• high-voltage insulators
• photonic crystal
• insulation defects
• portable diagnostic tool