scholarly journals Foreign Inclusions, Enclosed Cavities, Partial Discharge Models and Discharge Energy: A Short Review Regarding Solid Dielectrics and Composite Insulating Systems

2019 ◽  
Vol 9 (5) ◽  
pp. 4659-4666 ◽  
Author(s):  
M. Danikas ◽  
S. Morsalin
Keyword(s):  
Partial Discharge ◽  
Short Review ◽  
Partial Discharges ◽  
Discharge Energy ◽  
Insulating Materials ◽  
Discharge Parameters ◽  
Solid Dielectrics ◽  
The Relationship ◽  
Inception Voltage

Partial discharges in cavities are one of the main reasons of breakdown of insulating materials and insulating systems in general. The present paper aims at commenting some aspects of the relation between partial discharges and insulation damage. Some basic models explaining the workings and impacts of discharges in cavities are discussed. Discussions about the possibility of damage in the presence of multiple cavities as well as of the risks of minute discharges and/or charging phenomena below the so-called inception voltage are conducted. It is remarked that the question of the relationship between discharge parameters and insulation damage is still an important one, especially for composite insulating systems.

Comparative Analysis versus Frequency of Inception Voltage of Partial Discharges Phenomena and Breakdown Strength, in Support of Quality Assessment of Insulating Materials

2010 ◽  
Vol 437 ◽  
pp. 584-588
Author(s):  
Romeo Cristian Ciobanu ◽  
Cristina Schreiner
Keyword(s):  
Comparative Analysis ◽  
Quality Assessment ◽  
Measurement Technique ◽  
Breakdown Strength ◽  
Partial Discharge ◽  
Partial Discharges ◽  
Insulating Materials ◽  
Complementary Method ◽  
Inception Voltage

The broadband Partial Discharge (PD) measurement technique may be considered more accurate than a simple breakdown test and admitted as a complementary method for characterizing the quality of porous/fibrous and composite insulating materials. It should be taken into account especially at higher frequencies, when the risk of breakdown occurrence becomes greater in time, due to the local thermal aspects.

scholarly journals Study on the Correlation between Partial Discharge Energy and SF6 Decomposition Gas Generation

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4655
Author(s):  
Yong Sung Cho ◽  
Tae Yoon Hong ◽  
Young Woo Youn ◽  
Jong Ho Sun ◽  
Se-Hee Lee
Keyword(s):  
Partial Discharge ◽  
Surface Discharge ◽  
Discharge Energy ◽  
The Finite Element Method ◽  
Gas Generation ◽  
Energy Effect ◽  
Sf6 Decomposition ◽  
Maintenance Process ◽  
The Relationship

In this paper, the amount of SF6 decomposition gases due to the partial discharge (PD) was studied in the SF6 gas-insulated transformer. The long-term PD degradation experiment was performed while controlling the discharge magnitude using the surface discharge, and the gas generation amount was measured by using gas chromatography for SO2F2, SOF2, SO2, CO, and CF4. In addition, to investigate the relationship between the partial discharge energy and the decomposed gas generation amount, partial discharge energy was calculated by a data processing program and converted to the unit of joule per mole. With the finite element method (FEM), the electric field distribution and SF6 gas decomposition mechanism were explained for the partial discharge energy effect on the gas generation. This study helps understand the relationship between the partial discharge energy and the decomposed gas generation ratio with the experimental results and can be used for the diagnosis of PD and maintenance process for the gas-insulated transformers.

scholarly journals Partial Discharges in Cavities and their Connection with Dipoles, Space Charges, and Some Phenomena Below Inception Voltage

2020 ◽  
Vol 10 (4) ◽  
pp. 5869-5874
Author(s):  
G. E. Vardakis ◽  
M. Danikas ◽  
A. Nterekas
Keyword(s):  
Charge Distribution ◽  
Partial Discharge ◽  
Electromagnetic Theory ◽  
Partial Discharges ◽  
Charge Dynamics ◽  
Space Charges ◽  
Discharge Activity ◽  
Electric Dipoles ◽  
Inception Voltage

This paper tries to relate Pedersen’s model on partial discharges and work carried out by Bruning and co-workers on the possibility of the existence of charging phenomena below inception voltage, which may eventually cause deterioration of polymeric insulation. Moreover, with the aid of the Electromagnetic theory, some aspects of the Pedersen’s model are tried to be clarified, especially those which are correlated with space charges, electric dipoles, charge distribution, charge dynamics, and partial discharge activity.

scholarly journals Space Charges as Pre-breakdown Phenomena in Solid Dielectrics: A Concise Approach and Some Critical Comments

2020 ◽  
Vol 10 (4) ◽  
pp. 5992-5997
Author(s):  
M. Danikas ◽  
G. E. Vardakis ◽  
R. Sarathi
Keyword(s):  
Polymeric Materials ◽  
Short Review ◽  
Space Charges ◽  
Solid Dielectrics ◽  
The Relationship

This short review deals with some aspects of space charges in solid dielectrics, and in particular in polymeric materials. The relationship between space charges and pre-breakdown events is discussed and the importance of space charges for the breakdown of solid dielectrics is emphasized.

scholarly journals Insulating Materials at Very Low Temperatures: A Short Review

2020 ◽  
Vol 10 (3) ◽  
pp. 5590-5595 ◽  
Author(s):  
P. Malelis ◽  
M. Danikas
Keyword(s):  
Electrode Surface ◽  
Low Temperatures ◽  
Short Review ◽  
Partial Discharges ◽  
Future Research ◽  
Insulating Materials ◽  
Factors Affecting

In this paper, a short review is given on insulating materials at very low temperatures. Various insulating materials are investigated in terms of phenomena such as partial discharges. Some of the factors affecting the behavior of the insulating materials at very low temperatures, such as the quality of electrode surface, the stressed insulation volume and the existing bubbles, are also reported and commented upon. Proposals for future research are also discussed.

scholarly journals Comparative Tests of Partial Discharges in Nomex® 910 Paper and Cellulose Paper

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 647
Author(s):  
Hubert Moranda ◽  
Hanna Moscicka-Grzesiak ◽  
Piotr Przybylek ◽  
Krzysztof Walczak ◽  
Radoslaw Szewczyk
Keyword(s):  
Moisture Content ◽  
Partial Discharge ◽  
Mineral Oil ◽  
Partial Discharges ◽  
Comparative Tests ◽  
Cellulose Paper ◽  
Pure Cellulose ◽  
Insulation Systems ◽  
Four Levels ◽  
Inception Voltage

The article presents the results of comparative investigations of partial discharges in two insulation systems; aramid-enhanced cellulose paper-mineral oil, and pure cellulose paper-mineral oil. Partial discharges were investigated in a diagonal electric field with vertical and horizontal components. This field is treated as the most dangerous for insulation. The research was carried out on Nomex® 910 paper and cellulose paper samples, each paper being 0.25 mm thick. Samples of the two materials were tested at four levels of moisture. The inception voltage of partial discharges of all samples tested decreased as their moisture content increases. It was also proved that Nomex® 910 has a significantly higher partial discharge inception voltage than the cellulose paper, although this difference decreased with increasing moisture content.

scholarly journals Variability of the UHF Signals Generated by Partial Discharges in Mineral Oil

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1392 ◽  
Author(s):  
Michal Kunicki
Keyword(s):  
Glass Ceramic ◽  
High Frequency ◽  
Dielectric Materials ◽  
Mineral Oil ◽  
Partial Discharges ◽  
New Mineral ◽  
Relative Level ◽  
Solid Dielectrics ◽  
Inception Voltage

The paper presents the results of the analysis on the variability of the ultra-high frequency (UHF) signals generated by partial discharges (PD) under the long-term AC voltage. Surface PD (SD) are generated by model PD source (PDS) immersed in brand new mineral oil. Three scenarios are compared and investigated, where different solid dielectrics are applied: pressboard paper (PBP), polytetrafluoroethylene (PTFE) and glass-ceramic (GLS). The PDS is powered continuously by the AC voltage with its relative level of 1.3 of the inception voltage (Ui) within 168 h. UHF signals generated by the continuously occurred SD within 168 h are registered. Various indicators describing the variability of the UHF signals emitted by SD are assigned and analyzed in order to discover if there are any relevant trends presented. Furthermore, some long-term characteristics of the UHF signals emitted by the applied PDS are also announced. As a result, some relevant trends are discovered and related to the properties of the applied dielectric materials, thus the variability of the UHF signals emitted by SD is confirmed. The highest variability of the UHF signals is associated with PBP and the first 48 h after PD inception. Moreover achieved results may be potentially applied for modeling of the PD variability in time, which may be useful for works that concern the development of the UHF method.

scholarly journals A method to reduce partial discharges in motor windings fed by PWM inverter

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 599-604 ◽  
Author(s):  
Daniel Roger ◽  
Sonia Ait-Amar ◽  
Ewa Napieralska
Keyword(s):  
Partial Discharge ◽  
Partial Discharges ◽  
Conducting Layer ◽  
Element Analysis ◽  
New Approach ◽  
Pwm Inverter ◽  
Additional Layer ◽  
Ac Motor ◽  
Critical Zones ◽  
Inception Voltage

AbstractA new approach for designing ac motor windings free of partial discharges (PD) is proposed. The method consists of adding a thin conducting layer on the outer surface of the enameled wire used for building the machine winding. With this additional layer, PDs occur only in critical zones localized near the wire connections rather than randomly in the residual voids between turns. With such deterministic localizations, it is possible to reduce strongly the PD activity by adding small quantities of varnish in the determined critical zones. After studying the validity of the Paschen’s hypotheses for this application, the Paschen’s law is coupled to an electrostatic finite element analysis, for predicting the Partial Discharge Inception Voltage (PDIV), which corresponds to the electronic avalanche ignition in the air of critical zones.

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