scholarly journals Electrical Trees in a Composite Insulating System Consisted of Epoxy Resin and Mica: The Case of Multiple Mica Sheets For Machine Insulation

2014 ◽  
Vol 4 (4) ◽  
pp. 662-668 ◽  
Author(s):  
V. A. Kioussis ◽  
M. Danikas ◽  
D. D. Christantoni ◽  
G. E. Vardakis ◽  
Α. Bairaktari
Keyword(s):  
Cellular Automata ◽  
Epoxy Resin ◽  
Partial Discharges ◽  
Experimental Results ◽  
Rotating Machine ◽  
Electrical Tree ◽  
Electrical Trees ◽  
Simulation Results

Epoxy resin and mica sheets consist the essential insulation of rotating machine stator bars. Such an insulation, although very resistant to partial discharges, is subjected to considerable electrical stresses and consequently electrical trees may ensue. In this paper, an effort is  made to simulate electrical tree propagation in multiple epoxy resin/mica sheets with the aid of Cellular Automata (CA). An attempt to compare the simulation results with experimental results is also made.

scholarly journals Application of the Gaussian Mixture Model to Classify Stages of Electrical Tree Growth in Epoxy Resin

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2562
Author(s):  
Abdullahi Abubakar Mas’ud ◽  
Arunachalam Sundaram ◽  
Jorge Alfredo Ardila-Rey ◽  
Roger Schurch ◽  
Firdaus Muhammad-Sukki ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Gaussian Mixture Model ◽  
Mixture Model ◽  
Tree Growth ◽  
Asset Management ◽  
Gaussian Mixture ◽  
Growth Stages ◽  
Insulation Material ◽  
Electrical Tree ◽  
Electrical Trees

In high-voltage (HV) insulation, electrical trees are an important degradation phenomenon strongly linked to partial discharge (PD) activity. Their initiation and development have attracted the attention of the research community and better understanding and characterization of the phenomenon are needed. They are very damaging and develop through the insulation material forming a discharge conduction path. Therefore, it is important to adequately measure and characterize tree growth before it can lead to complete failure of the system. In this paper, the Gaussian mixture model (GMM) has been applied to cluster and classify the different growth stages of electrical trees in epoxy resin insulation. First, tree growth experiments were conducted, and PD data captured from the initial to breakdown stage of the tree growth in epoxy resin insulation. Second, the GMM was applied to categorize the different electrical tree stages into clusters. The results show that PD dynamics vary with different stress voltages and tree growth stages. The electrical tree patterns with shorter breakdown times had identical clusters throughout the degradation stages. The breakdown time can be a key factor in determining the degradation levels of PD patterns emanating from trees in epoxy resin. This is important in order to determine the severity of electrical treeing degradation, and, therefore, to perform efficient asset management. The novelty of the work presented in this paper is that for the first time the GMM has been applied for electrical tree growth classification and the optimal values for the hyperparameters, i.e., the number of clusters and the appropriate covariance structure, have been determined for the different electrical tree clusters.

scholarly journals Effect of Air Gap on Electrical Tree in Epoxy Resin Under High Frequency Bipolar Square-Wave Voltage

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5722
Author(s):  
Shihang Wang ◽  
Chuang Zhang ◽  
Hang Fu ◽  
Jiao Xiang ◽  
Jianying Li ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
High Frequency ◽  
Air Gap ◽  
Heat Accumulation ◽  
Air Gaps ◽  
Square Wave ◽  
Electrical Tree ◽  
Electrical Trees ◽  
Voltage Frequency ◽  
Tree Characteristics

Insulation fails quickly under high-frequency AC high voltage, especially bipolar square-wave voltage with a high dV/dt. It is of great significance to study the failure mechanism of epoxy casting insulation under such kind of voltage. In this paper, pin-plane epoxy casting insulation samples with air gaps were prepared, and the relation between the electrical trees under the high frequency bipolar square-wave voltage and the air gap conditions and voltage frequencies (1~20 kHz) were studied. Results indicated that, with the presence of air gaps, the electrical trees were bush-type and had a relatively slow growth rate, which was different from the fast-growing branch-type trees in the samples without air gap. The electrical tree characteristics related with the size of air gap and voltage frequency were also studied. The electrical tree grew faster under higher voltage frequency or with a smaller air gap. Results proved that discharge introduced a lot of defects for the surface layer of the epoxy resin samples and hence induced the possibility of multi-directional expansion of electrical trees. In addition, the resulting heat accumulation and unique charge transport synergistically affected the electrical tree characteristics under the high frequency bipolar square-wave voltage.

SUBCONSCIOUS ENVIRONMENTAL INFORMATION PERCEIVING BEHAVIOR AND ITS ATTENUATION IN INFORMATION-BASED EVACUATION EXPERIMENT

2012 ◽  
Vol 23 (07) ◽  
pp. 1250049 ◽  
Author(s):  
LIZHONG YANG ◽  
SHAOBO LIU ◽  
PING RAO ◽  
KONGJIN ZHU
Keyword(s):  
Cellular Automata ◽  
Flow Rate ◽  
Normal Condition ◽  
Emergency Evacuation ◽  
Environmental Information ◽  
Experimental Results ◽  
Cellular Automata Model ◽  
Human Behaviors ◽  
Simulation Results ◽  
Evacuation Experiment

An evacuation was studied from a classroom by means of experiment and simulation. In the experiments, evacuation with and without visibility was mimicked by requiring the evacuees to wear eye masks or not. The distribution of evacuees' egress times against initial positions and the flow rate at exits were studied. It was found that when masks were used, evacuees' egress strategies were highly dependent on their pre-perceived environmental information in subconsciousness which might affect the egress process. Thus we call this phenomenon the "subconscious environmental information perceiving behavior." In the simulation, a cellular automata model considering the influence of sound information and the subconscious behavior was used to simulate the experiments. Both the experimental and the simulation results show that the sound information plays a more important role in evacuation without visibility than in normal condition, and the pre-perceived environmental information is also very important when people have poor visibility because of the subconscious environmental information perceiving behavior. The simulation results consist with the experimental results well. This study is useful for understanding the human behaviors during emergency evacuation with poor visibility under the guide of sound signal.

A 2D CELLULAR AUTOMATA MODEL FOR TREE PROPAGATION IN NANOCOMPOSITES: INFLUENCE OF THE NANOPARTICLES SIZE, LOADING AND THE PRESENCE OF MICROVOIDS

NANO ◽  
2013 ◽  
Vol 08 (01) ◽  
pp. 1350002 ◽  
Author(s):  
DESPOINA PITSA ◽  
MICHAEL G. DANIKAS
Keyword(s):  
Cellular Automata ◽  
Polymer Nanocomposites ◽  
Polymer Nanocomposite ◽  
Epoxy Nanocomposites ◽  
Cellular Automata Model ◽  
Dc Voltage ◽  
Electrical Tree ◽  
Electrical Trees ◽  
Ca Model ◽  
Tree Length

Electrical tree propagation in a polymer nanocomposite is affected by the presence of nanoparticles. A 2D cellular automata (CA) model is presented for the simulation of electrical tree propagation in polymer nanocomposites. The effect of the nanoparticles size, the nanoparticles loading and the appearance of microvoids on electrical tree propagation in titania ( TiO2 )/epoxy nanocomposites under the application of DC voltage is examined with the aid of the CA model. It has been observed that the tree length is affected by nanoparticles size and nanoparticles loading. A resistance in electrical tree propagation has been noticed, as nanoparticles size decreases or as nanoparticles loading increases. The presence of microvoids in the polymer nanocomposite is another factor that has been examined. The propagation of electrical trees that initiate from microvoids in the polymer nanocomposite has also been simulated by the use of the CA model.

scholarly journals Influence of Repetitive Square Voltage Duty Cycle on the Electrical Tree Characteristics of Epoxy Resin

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2215 ◽  
Author(s):  
Peng Wang ◽  
Suxin Hui ◽  
Shakeel Akram ◽  
Kai Zhou ◽  
Muhammad Tariq Nazir ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Duty Cycle ◽  
Electronic Device ◽  
Wide Band ◽  
Shielding Effect ◽  
Power Electronic ◽  
Square Wave ◽  
Electrical Tree ◽  
Duty Cycles ◽  
Electrical Trees

The application of wide band-gap power electronic devices brings more challenges to insulating packaging technology. Knowing the influence of applied voltage parameters on insulation performance is helpful to evaluate the insulation condition of electric power equipment. In this paper, the effect of repetitive square wave voltage duty cycle on the growth characteristics of electrical trees in epoxy resin was studied. The experimental results show that the square wave voltage duty cycle has a significant influence on treeing features. The electrical tree proportion initiation has shown a decreasing trend, and the shape of the electrical tree changes from pine-like to branch-like by increasing the duty cycles. The length and damaged area of electrical tree increased with the increase in the duty cycle up to 10% and then decrease by increasing the duty cycle higher than 30%. It indicates that a low duty cycle will enhance the electron injection and accumulate space charges and thus accelerate electrical tree development. Under short duty cycles, the electric field due to the shielding effect near the needle tip suppresses the electrical tree growth, which results in treeing growth stagnation. The obtained results are helpful to keep these parameters in mind during the design of epoxy-based insulation such high-voltage rotating machines and power electronic device packaging.

Radiated Electro-Magnetic Waves Caused by Electrical Tree Development in Epoxy Resin

2009 ◽  
Vol 129 (12) ◽  
pp. 915-921 ◽  
Author(s):  
Hideki Ueno ◽  
Takashi Nagamachi ◽  
Masaki Nakamura ◽  
Hiroshi Nakayama ◽  
Kunihiko Kakihana
Keyword(s):  
Epoxy Resin ◽  
Electrical Tree ◽  
Electro Magnetic ◽  
Tree Development ◽  
Magnetic Waves

scholarly journals The Development of Electrical Tree Discharge in Epoxy Resin Impregnated Paper Insulation

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 69522-69531
Author(s):  
Yongqiang Wang ◽  
Changhui Feng ◽  
Yu Luo
Keyword(s):  
Epoxy Resin ◽  
Electrical Tree ◽  
Paper Insulation
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