ELECTRIC FIELDS FOR PREBREAKDOWN PARTIAL DISCHARGES IN LIQUID DIELECTRICS

1971 ◽  
Vol 18 (11) ◽  
pp. 513-515
Author(s):  
Alfred Fafarman
Keyword(s):  
Electric Fields ◽  
Partial Discharges ◽  
Liquid Dielectrics

scholarly journals Using contactless methods of diagnostics of high electric fields

2019 ◽  
Vol 21 (4) ◽  
pp. 123-133
Author(s):  
A. V. Golenischev-Kutuzov ◽  
D. A. Ivanov ◽  
A. A. Potapov ◽  
V. I. Krotov
Keyword(s):  
Electric Fields ◽  
High Voltage ◽  
Optical Sensors ◽  
Electric Power Industry ◽  
Dielectric Materials ◽  
Partial Discharges ◽  
Contact Method ◽  
Diagnostic Device ◽  
Measuring Device ◽  
Remote Diagnostics

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.

Particle behaviour in shear and electric fields I. Deformation and burst of fluid drops

1962 ◽  
Vol 267 (1328) ◽  
pp. 45-61 ◽  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Quantitative Agreement ◽  
Dielectric Constants ◽  
Liquid Drops ◽  
Electrical Fields ◽  
Oblate Spheroids ◽  
Prolate Spheroids ◽  
Combined Action ◽  
Liquid Dielectrics

The deformation and burst of liquid drops suspended in liquid dielectrics in an electric field were measured. At low electrical fields, the deformation of conducting drops into prolate spheroids showed good quantitative agreement with theoretical equations based on electrostatic theory. Dielectric drops exhibited appreciable deviation from the theory, especially in a number of system s w hen oblate spheroids were formed. The mode of electrical burst was found to show considerable variation with the electrical properties of the systems. The deformation, orientation and burst under the combined action of shear and electric fields were also studied and found to agree with a theory based upon a superposition of electric- and shear-deformation forces. The mode of break-up was found to depend on the ratio of the velocity gradient to the electric field strength, on the interfacial tension, and on the ratios of dielectric constants and of viscosities of the two liquids.

scholarly journals Study of Water Droplets Behavior on Electrical Machine Insulation Under the Influence of Uniform Electric Fields: the Influence of Some Parameters on Mica Sheets

2018 ◽  
Vol 8 (1) ◽  
pp. 2351-2355 ◽  
Author(s):  
M. Danikas ◽  
S. Maslougkas
Keyword(s):  
Electric Fields ◽  
Partial Discharges ◽  
Electrical Machine ◽  
Water Droplets ◽  
Effect Of Water ◽  
Flashover Voltage ◽  
Surface Discharges ◽  
Vital Component

Mica sheets are a vital component of electrical machine insulation. Although great attention has been paid to partial discharges and their deteriorating effect on such insulation, relatively little attention has been given to surface discharges. This paper investigates the effect of water droplets, their volume, their conductivity, their positioning as well as their number on the flashover voltage of mica sheets. It is indicated that all the above mentioned parameters influence the flashover voltage

Sign in / Sign up

Export Citation Format

Share Document