Epoxy resin insulation: The influence of nanoparticles on the flashover voltage and possible alternatives for Electrical Machines Insulation

2016 ◽  
Author(s):  
M. G. Danikas ◽  
K. Varsamidou ◽  
Y. Cheng ◽  
A. D. Karlis
Keyword(s):  
Epoxy Resin ◽  
Electrical Machines ◽  
Flashover Voltage

scholarly journals Investigation of Factors Affecting Partial Discharges on Epoxy Resin: Simulation, Experiments, and Reference on Electrical Machines

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6621
Author(s):  
Dimosthenis Verginadis ◽  
Athanasios Karlis ◽  
Michael G. Danikas ◽  
Jose A. Antonino-Daviu
Keyword(s):  
Power Systems ◽  
Epoxy Resin ◽  
Partial Discharges ◽  
Electrical Machines ◽  
Synchronous Generators ◽  
Water Conductivity ◽  
High Mechanical Strength ◽  
Factors Affecting ◽  
Simulink Model ◽  
Flashover Voltage

In Power Systems, Synchronous Generators (SGs) are mostly used for generating electricity. Their insulation system, of which epoxy resin is a core component, plays a significant role in reliable operation. Epoxy resin has high mechanical strength, a characteristic that makes it a very good material for reliable SG insulation. Partial Discharges (PDs) are a constant threat to this insulation since they cause deterioration and consequential degradation of the aforementioned material. Therefore, it is very important to detect PDs, as they are both a symptom of insulation deterioration and a means to identify possible faults. Offline and Online PDs Tests are described, and a MATLAB/Simulink model, which simulates the capacitive model of PDs, is presented in this paper. Moreover, experiments are carried out in order to examine how the flashover voltage of epoxy resin samples is affected by different humidity levels. The main purpose of this manuscript is to investigate factors, such as the applied voltage, number, and volume of water droplets and water conductivity, which affect the condition of epoxy resin, and how these are related to PDs and flashover voltages, which may appear also in electrical machines’ insulation. The aforementioned factors may affect the epoxy resin, resulting in an increase in PDs, which in turn increases the overall Electrical Rotating Machines (EMs) risk factor.

scholarly journals A Study of the Behaviour of Water Droplets Under the Influence of Uniform Electric Field in Epoxy Resin Samples

2012 ◽  
Vol 63 (3) ◽  
pp. 196-200 ◽  
Author(s):  
Yonghong Cheng ◽  
Xu Zhao ◽  
Michael Danikas ◽  
Despoina Christantoni ◽  
Pavlos Zairis
Keyword(s):  
Electric Field ◽  
Epoxy Resin ◽  
Electric Fields ◽  
Uniform Electric Field ◽  
Droplet Volume ◽  
Water Droplets ◽  
Water Conductivity ◽  
Volume Number ◽  
Flashover Voltage ◽  
Droplet Behavior

A Study of the Behaviour of Water Droplets Under the Influence of Uniform Electric Field in Epoxy Resin SamplesWater droplets on the surface of epoxy resin samples were investigated under the influence of uniform electric fields. Several parameters of water droplets were investigatedwrtthe flashover voltage of the epoxy resin samples, such as water conductivity, droplet volume, number of droplets as well as the positioning of the droplets regarding the electrodes. The droplet behavior is affected by the above mentioned parameters. Perhaps the most striking conclusion is that the flashover voltage depends more on the positioning of the dropletswrtthe electrodes than on the droplet volume and/or number of droplets.

scholarly journals Behaviour of Water Droplets Under the Influence of a Uniform Electric Field in Nanocomposite Samples of Epoxy Resin/TiO2

2013 ◽  
Vol 3 (5) ◽  
pp. 511-515 ◽  
Author(s):  
Α. Bairaktari ◽  
M. Danikas ◽  
X. Zhao ◽  
Y. Cheng ◽  
Y. Zhang
Keyword(s):  
Electric Field ◽  
Epoxy Resin ◽  
Tio2 Nanoparticles ◽  
Water Droplet ◽  
Uniform Electric Field ◽  
Droplet Volume ◽  
Water Droplets ◽  
Water Conductivity ◽  
Flashover Voltage

In this paper nanocomposite samples of epoxy resin and TiO2 nanoparticles were investigated with water droplets on their surface. A uniform electric field was applied and the behaviour of the water droplets was observed. Parameters that were studied were the water conductivity, the droplet volume, the number of droplets and the droplet positioning with respect to (w.r.t.) the electrodes. All above mentioned parameters influence the flashover voltage of the samples. It is to be noted that – at least in some cases – the water droplet positioning w.r.t. the electrodes was more important in determining the flashover voltage than the droplet volume.

scholarly journals Perkiraan Tegangan Lewat Denyar Isolator Tegangan Menengah 20 kV Keramik dan Resin Epoksi berdasarkan Data Arus Bocor

2019 ◽  
Vol 11 (1) ◽  
pp. 34-38
Author(s):  
Valdi Rizki Yandri ◽  
Herisajani Herisajani ◽  
Fitriadi Fitriadi
Keyword(s):  
Fourier Transform ◽  
Epoxy Resin ◽  
Leakage Current ◽  
Current Data ◽  
Digital Data ◽  
High Humidity ◽  
Climate Conditions ◽  
Digital Oscilloscope ◽  
Flashover Voltage ◽  
High Pollution

This paper explains the research results of leakage current data and estimation of flashover voltage on ceramics and epoxy resin as 20 kV outdoor insulator in a chamber with tropical climate conditions. The waveform of leakage current (LC) was measured using a digital oscilloscope. The digital data was transferred to a personal computer using a RS-232 cable. The digital data was analyzed using Fast Fourier Transform. The result showed that LC was affected by various environment conditions like temperature, humidity and pollution. LC of ceramics insulator was higher than epoxy resin insulator in low temperature, high humidity and high pollution condition.

scholarly journals Effect of Bismuth Ferrite Nanometer Filler Element Doping on the Surface Insulation Properties of Epoxy Resin Composites

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2200
Author(s):  
Jun Xie ◽  
Chaoxuan Xiao ◽  
Shuai Shao ◽  
Qijun Duan ◽  
Qing Xie ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Dissipation Rate ◽  
Mass Fraction ◽  
Bismuth Ferrite ◽  
Resin Composites ◽  
Element Doping ◽  
Flashover Voltage ◽  
Epoxy Resin Composites ◽  
Filler Mass ◽  
Co Doped

In the direct current electric field, the surface of epoxy resin (EP) insulating material is prone to charge accumulation, which leads to electric field distortion and damages the overall insulation of the equipment. Nano-doping is an effective method to improve the surface insulation strength and DC flashover voltage of epoxy resin composites. In this study, pure bismuth ferrite nanoparticles (BFO), as well as BFO nanofillers, which were doped by La element, Cr element as well as co-doped by La + Cr element, were prepared by the sol-gel method. Epoxy composites with various filler concentrations were prepared by blending nano-fillers with epoxy resin. The morphology and crystal structure of the filler were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. The effects of different filler types and filler mass fraction on the surface flashover voltage, charge dissipation rate, and trap characteristics of epoxy resin composites were studied. The results showed that element doping with bismuth ferrite nanofillers could further increase the flash voltage of the composites. The flashover voltage of La + Cr elements co-doped composites with the filler mass fraction of 4 wt% was 45.2% higher than that of pure epoxy resin. Through data comparison, it is found that the surface charge dissipation rate is not the only determinant of the flashover voltage. Appropriately reducing the surface charge dissipation rate of epoxy resin composites can increase the flashover voltage. Finally, combining with the distribution characteristics of the traps on the surface of the materials to explain the mechanism, it is found that the doping of La element and Cr element can increase the energy level depth and density of the deep traps of the composite materials, which can effectively improve the flashover voltage along the surface of the epoxy resin.

Ultrastructural investigation of spontaneous pituitary gonadotroph cell adenomas in aging Sprague-Dawley rats

1983 ◽  
Vol 41 ◽  
pp. 702-703
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Electron Microscopy ◽  
Animal Model ◽  
Epoxy Resin ◽  
Immunoelectron Microscopy ◽  
Tumor Type ◽  
Gonadal Function ◽  
Sprague Dawley ◽  
Male And Female ◽  
Reticulin Fibers ◽  
Sprague Dawley Rats

Gonadotroph cell adenomas of the pituitary are infrequent in human patients and are not invariably associated with altered gonadal function. To date, no animal model of this tumor type exists. Herein, we describe spontaneous gonadotroph cell adenomas in old male and female Sprague-Dawley rats by histology, immunocytology and electron microscopy.The material consisted of the pituitaries of 27 male and 38 female Sprague Dawley rats, all 26 months of age or older, removed at routine autopsy. Sections of formal in-fixed, paraffin-embedded tissue were stained with hematoxylin-phloxine-saffron (HPS), the PAS method and the Gordon-Sweet technique for the demonstration of reticulin fibers. For immunostaining, sections were exposed to anti-rat β-LH, anti-ratβ-TSH, anti-rat PRL, anti-rat GH and anti-rat ACTH 1-39. For electron microscopy, tissue was fixed in 2.5% glutaraldehyde, postfixed in 1% OsO4 and embedded in epoxy-resin. Tissue fixed in 10% formalin, embedded in epoxy resin without osmification, was used for immunoelectron microscopy.

Surface Structure in Microtomed Sections Caused by Glass and Diamond Knives

1971 ◽  
Vol 29 ◽  
pp. 456-457
Author(s):  
J. Temple Black ◽  
William G. Boldosser
Keyword(s):  
Plastic Deformation ◽  
Epoxy Resin ◽  
Carbon Coating ◽  
Surface Damage ◽  
Body Angle ◽  
Normal Manner ◽  
Bottom Side ◽  
Cutting Direction ◽  
Made In ◽  
Diamond Knife

Ultramicrotomy produces plastic deformation in the surfaces of microtomed TEM specimens which can not generally be observed unless special preparations are made. In this study, a typical biological composite of tissue (infundibular thoracic attachment) infiltrated in the normal manner with an embedding epoxy resin (Epon 812 in a 60/40 mixture) was microtomed with glass and diamond knives, both with 45 degree body angle. Sectioning was done in Portor Blum Mt-2 and Mt-1 microtomes. Sections were collected on formvar coated grids so that both the top side and the bottom side of the sections could be examined. Sections were then placed in a vacuum evaporator and self-shadowed with carbon. Some were chromium shadowed at a 30 degree angle. The sections were then examined in a Phillips 300 TEM at 60kv.Carbon coating (C) or carbon coating with chrom shadowing (C-Ch) makes in effect, single stage replicas of the surfaces of the sections and thus allows the damage in the surfaces to be observable in the TEM. Figure 1 (see key to figures) shows the bottom side of a diamond knife section, carbon self-shadowed and chrom shadowed perpendicular to the cutting direction. Very fine knife marks and surface damage can be observed.

Epoxy Resin Embedment

1968 ◽  
Vol 26 ◽  
pp. 100-101
Author(s):  
J. G. Adams ◽  
M. M. Campbell ◽  
H. Thomas ◽  
J. J. Ghldonl
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Epoxy Resin ◽  
Light Microscope ◽  
Epoxy Resins ◽  
Image Contrast ◽  
Tissue Preservation ◽  
Resin System ◽  
Excellent Quality

Since the introduction of epoxy resins as embedding material for electron microscopy, the list of new formulations and variations of widely accepted mixtures has grown rapidly. Described here is a resin system utilizing Maraglas 655, Dow D.E.R. 732, DDSA, and BDMA, which is a variation of the mixtures of Lockwood and Erlandson. In the development of the mixture, the Maraglas and the Dow resins were tested in 3 different volumetric proportions, 6:4, 7:3, and 8:2. Cutting qualities and characteristics of stability in the electron beam and image contrast were evaluated for these epoxy mixtures with anhydride (DDSA) to epoxy ratios of 0.4, 0.55, and 0.7. Each mixture was polymerized overnight at 60°C with 2% and 3% BDMA.Although the differences among the test resins were slight in terms of cutting ease, general tissue preservation, and stability in the beam, the 7:3 Maraglas to D.E.R. 732 ratio at an anhydride to epoxy ratio of 0.55 polymerized with 3% BDMA proved to be most consistent. The resulting plastic is relatively hard and somewhat brittle which necessitates trimming and facing the block slowly and cautiously to avoid chipping. Sections up to about 2 microns in thickness can be cut and stained with any of several light microscope stains and excellent quality light photomicrographs can be taken of such sections (Fig. 1).

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