M. BELHITECHE El'hadi

MCB

Directory of teachers

Department

BASE COMMON ST Departement ST

Research Interests

Caractérisation des polymères isolants avant et après vieillissement ( Electrique et/ou Thermique)

Contact Info

University of M'Sila, Algeria

Email : el'hadi.belhiteche@univ-msila.dz

On the Web:

  • Google Scholar N/A
  • ResearchGate
    ResearchGate N/A
  • ORCID N/A
  • SC
    Scopus N/A

Recent Publications

2024-11-09

Effect of AC Corona Discharge on Dielectric Properties of Polymers

Abstract— Polymers have many advantages over conventional insulation such as glass, porcelain and impregnated paper. They have better mechanical properties, lower wettability and they are lighter and carried out more easily. However, they are vulnerable to the action of surface discharges which are responsible for their degradation. A discharge, which occurs on the surface of the polymer, causes aging followed by the destruction of the insulator, whose physicochemical mechanisms are not yet well understood.
The work in this paper is a comparative study to better understand the effects of the corona discharge on polymethyl methacrylate (PMMA), styrene acrylonitrile (SAN) and epoxy resin. The insulation performance of these three materials was evaluated through scanning electron microscopy observations; dielectric spectroscopy and Fourier transform infrared spectroscopy analysis. Polymers subjected to a corona discharge undergo a degradation which results in the rupture of some chemical bonds and the formation of hydroxyl groups OH which could enhance surface conduction. For the Polymethyl methacrylate, we highlighted the phenomenon of degradation by a significant development of trees on the dielectric surface. We observe that the permittivity decreases with the increase of both the frequency and the aging time under corona discharge.
Keywords— Corona discharge, dielcctric properties, surface degradation, trees.
Citation

M. BELHITECHE El'hadi, (2024-11-09), "Effect of AC Corona Discharge on Dielectric Properties of Polymers", [international] 4th International Conference on Electronics and Electrical Engineering (IC3E'2024) , Bouira, Algérie

Read Full Paper
2022

Effect of aging time on the hydrophobicity of polymers subjected to corona discharge

In this work, we present the results of an experimental study on the effects of corona discharge on the hydrophobicity of insulating solids: Polymethyl methacylate (PMMA) and Styrene acrylonitrile (SAN). The evolution of the surface condition of the samples is characterized by measuring the contact angle formed by a drop of liquid (water) deposited on the surface of the sample (PMMA, SAN) and calculating the adhesion energy as a function of the duration of application of the electrical stress. We found that the contact angle and the adhesion energy depend on the physico-chemical properties of the surface, and the duration of the stress application. We also evaluated the state of degradation of these insulators by analysis by Fourier transform infrared spectrometry (FTIR).
Keywords — FTIR analyses, contact angle, surface degradation, hydrophobicity.
Citation

M. BELHITECHE El'hadi, (2022), "Effect of aging time on the hydrophobicity of polymers subjected to corona discharge", [international] The 2022 International Conference of Advanced Technology in Electronic and Electrical Engineering , Msila, Algérie

Read Full Paper

Physical characterization of polymers exposed to corona discharge

Polymers have many advantages over conventional insulation such as glass, porcelain and impregnated paper. They have better mechanical properties, lower wettability and they are lighter and carried out more easily. However, they are vulnerable to the action of surface discharges which are responsible for their degradation. A discharge, which occurs on the surface of the polymer, causes aging followed by the destruction of the insulator, whose physicochemical mechanisms are not yet well understood.
The work in this paper is a comparative study to better understand the effects of the corona discharge on polymethyl methacrylate (PMMA), styrene acrylonitrile (SAN) and epoxy resin. The insulation performance of these three materials was evaluated through scanning electron microscopy observations; dielectric spectroscopy and Fourier transform infrared spectroscopy analysis. Polymers subjected to a corona discharge undergo a degradation which results in the rupture of some chemical bonds and the formation of hydroxyl groups OH which could enhance surface conduction. For the Polymethyl methacrylate, we highlighted the phenomenon of degradation by a significant development of trees on the dielectric surface. We observe that the permittivity decreases with the increase of both the frequency and the aging time under corona discharge.
.
Keywords: Corona discharge, electrical aging, polymers, surface degradation, trees.
Citation

M. BELHITECHE El'hadi, (2022), "Physical characterization of polymers exposed to corona discharge", [international] The 7th International Conference on Mechanics and Energy (ICME 2022) , Hammamet, Tunisie

Read Full Paper

Effects of partial discharges on epoxy resin used in the insulation of electrical machines

Abstract:
In electrical machines, particularly those used in the medium and high voltage range, partial discharges between turns and between turns and ground constitute a significant cause of the aging of insulators. In this work, we present the results of an experimental study on the effects of partial discharges on the electrical and dielectric properties of insulating varnishes of electrical machines. The evolution of the intrinsic dielectric properties of these materials such as the relative permittivity, the resistivity and the dissipation factor are measured by the technique of dielectric spectrometry in a frequency range (1kHz – 10 kHz). The results of these measurements are discussed according to the duration of application of the electrical stress. The relative permittivity, the electrical resistivity and the dielectric loss factor depend on the frequency and the duration of the application of the electric field. The state of degradation of the insulator is evaluated by observations with a scanning electron microscope (SEM) and by analyzes by Fourier transform infrared spectrometry (FTIR). The micrographs showed that above a certain voltage value significant erosion occurs on the surface of the dielectric subjected to electric discharges. The discharge currents depend on the duration of application and the applied voltage level.
Keywords: FTIR analyses, partial discharges, surface degradation, SEM micrographs, epoxy resin.
Citation

M. BELHITECHE El'hadi, (2022), "Effects of partial discharges on epoxy resin used in the insulation of electrical machines", [international] International Conference on Mechanics and Energy , Hammamet, Tunisie

Read Full Paper
2021

Electrical insulation properties of silicone rubber under accelerated corona and thermal aging

A contactless method based on energy shift of high-energy cut-off of the x-ray bremsstrahlung, the so-called Duane Hunt Limit and a conventional low voltage electrical technique (three-probes technique) is applied on thermal and
corona aged silicone rubber (SiR) to measure, respectively, the surface potential, Vs, and the surface resistivity, ρs. The effect of aging on these quantities, representing the dielectric properties, is studied. The results are highly reproducible and highlight a good correlation between Vs and ρs. It was observed that thermal aging combined with electrical aging deteriorates more the electrical properties of the polymer than thermal aging alone. Explanations for electrical characteristics (Vs, ρs) change with aging are supported by attenuated total reflection Fourier transform infrared spectroscopy spectra analysis and a chemical mechanism of aging in three steps (i.e., oxidation-polycondensation, degradation, and thermal cracking). The surface degradation of the polymer is revealed by images of surface morphology obtained by using scanning electron microscopy (SEM). Roughness is greater for combined thermal and corona aging mode compared to thermal aging alone. In addition, the surface degradation of SiR polymer is confirmed by the loss of its hydrophobicity.

KEYWORDS
corona discharge, electrical properties, FTIR-ATR, silicone rubber, surface degradation, thermal aging.
Citation

M. BELHITECHE El'hadi, (2021), "Electrical insulation properties of silicone rubber under accelerated corona and thermal aging", [national] Polymer Engineering and Science , WILEY

Read Full Paper
2019

Chemical and Electrical Characterization of Polyvinyl Chloride (PVC) Under Electrical Aging

Abstract – Polyvinyl chloride is one of the most polymers used in electrical cable insulation. It has a greater resistance to moisture and abrasion and an excellent resistance to high temperature and good mechanical properties.
However under the action of electric field, the surface of the polymer is degraded. This degradation caused by irreversible changes in the material can rapidly shorten lifetime. The chemical reactions occurring in the process are: cross-linking reactions between the chains, oxidation, hydrolyses...etc. The kinetics of degradation depends on the concentration of the different constituents of the polymer. This paper presents an experimental study the effect of electrical aging on surface degradation of the polyvinyl chloride. We have subjected the samples (PVC) to AC voltage in plane-plane electrodes geometry during 10 hours. The PVC material used in the present investigation is employed as insulation for medium voltage (MV) cables (18/30 kV). The goal of this paper was to investigate the degradation of PVC insulation under electrical aging effect by characterization techniques. For this purpose, measurements of dielectric losses factor, relative permittivity, and volume resistivity were performed for each applied voltage as a function of aging time and frequency (500 Hz – 104 Hz). Based on the obtained results, the electrical aging influences slightly the dielectric constant. However, we observed a significant degradation of the used material (PVC) under the aging conditions abovementioned. This degradation is characterized by the dissipation factor increase and the decrease of volume resistivity. Morphology and surface chemistry of the PVC before and after aging were also investigated through scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. Aging had a significant impact on the surface of specimens. The un-aged sample had a smooth and homogenous surface. However, after the ageing test, it was found that damages caused by electrical stress occurred at the surface and craters were exhibited.
Keywords — Aging, electrical properties, FTIR, PVC, SEM.
Citation

M. BELHITECHE El'hadi, (2019), "Chemical and Electrical Characterization of Polyvinyl Chloride (PVC) Under Electrical Aging", [international] The Electrical Engineering International Conference , Bejaia, Algérie

Read Full Paper
2016

Caractérisation diélectrique du polyéthylène réticulé chimiquement soumis a la contrainte thermique

Résumé— L’utilisation prépondérante du polyéthylène réticulé chimiquement (PRC) dans l’isolation des câbles moyenne et haute tension est attribuée à ses excellentes propriétés électriques, thermiques et mécaniques. Cependant, cette isolation peut subir de cruciales dégradations sous les différentes contraintes.
Sous les conditions de service, les câbles sont en permanence assujettis à la contrainte thermique qui conduit à des altérations irréversibles de l’isolation en PRC. Ce travail présente un suivi de l’effet de la température sur les propriétés diélectriques du PRC utilisé comme isolation de câbles de haute tension. Les résultats obtenus montrent que la contrainte thermique affecte considérablement les propriétés de l’isolation.
Mots-clés— Polyéthylène réticulé chimiquement(PRC), MEB, rupture, traction, angle de contact.
Citation

M. BELHITECHE El'hadi, HEDIR Abdallah, , (2016), "Caractérisation diélectrique du polyéthylène réticulé chimiquement soumis a la contrainte thermique", [international] 10ème CONFÉRENCE DE LA SOCIÉTÉ FRANÇAISE ÉLECTROSTATIQUE (SFE) , Poitiers, France

Read Full Paper
← Back to Researchers List