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Simpy Sanyal,Taeyong Kim,Junsin Yi 대한전기학회 2022 대한전기학회 학술대회 논문집 Vol.2022 No.10
The influence of temperature, pollutant, and pH on the local corrosion rate of insulators installed in industrial, marine and rural installation sites are investigated based on experimental and statistical investigations. The tensile load test confirms corroded insulator specimens collected from industrial sites aged more than 10 years represent minimum fracture load, 19,892 lbs. It was further observed that more than 91.24% and 64.62% corroded insulator specimens suffered from shell break and pin detachment, respectively. The microstructural and XRF analysis reveal insulator specimens collected from industrial sites (age >10years), represented highest wt% of O (19.2) and lowest wt% of Zn (0.34) among industrial, marine, and rural installation sites. The The 3D stationery mechanical simulation reveals, insulator specimens aged >10 years experienced maximum stress (600MPa) in pin-cement interface. Using Full two-level factorial designs, Temperature, Concentration of pollutants and pH were found significant factors for Corrosion rate. The immersion test results further confirm the above-mentioned factors significant for the dissolution behavior of galvanized coating of insulator pin. In accordance with immersion test results the industrial region show highest corrosion rate (5.58-12 ㎛/year) among all installation sites.
Simpy Sanyal,Taeyong Kim,Junsin Yi 대한전기학회 2022 대한전기학회 학술대회 논문집 Vol.2022 No.10
The evaluation of Cerium based coating quality, reliability and suitability for insulator pin is governed by micro-structure analysis, hardness, adhesive strength between coating and substrate, surface binding energy, corrosion resistance as well as lifetime of coatings. After immersion in 60,000 PPM CeCl₃.7H₂O coating bath for 7 days, coatings consist of Ce rich dense protective film (24 ㎛). The Energy Dispersive X-Ray Spectroscopy EDS and X-Ray photoelectron spectroscopy XPS confirm 85.4% rise in weight (%) of Ce with immersion time. The Scanning Electron Microscope SEM and Vickers hardness test reveals cracks in coating film along with 1.5% decrease in microhardness with immersion time higher than 7 days. At the same time optimized coated specimens represent around 16.09% added hardness in contrast to bare specimens. The adhesive and interface strength of coating-substrate system are evaluated by X-cut Tape test and Cohesive Zone Finite Element approach CZM. The chemical bonding and binding energy intensity of coated specimens were investigated in detail by XPS. The lifetime expectancy of galvanised coating for coated specimens is 2.5 times more in opposed to bare specimens.
Hole Selective Contacts: A Brief Overview
Simpy Sanyal,DUTTA SUBHAJIT,Minkyu Ju,Kumar Mallem,Swagata Panchanan,조은철,조영현,이준신 한국태양광발전학회 2019 Current Photovoltaic Research Vol.7 No.1
Carrier selective solar cell structure has allured curiosity of photovoltaic researchers due to the use of wide band gap transition metal oxide (TMO). Distinctive p/n-type character, broad range of work functions (2 to 7 eV) and risk free fabrication of TMO has evolved new concept of heterojunction intrinsic thin layer (HIT) solar cell employing carrier selective layers such as MoOx, WOx, V2O5 and TiO2 replacing the doped a-Si layers on either front side or back side. The p/n-doped hydrogenated amorphous silicon (a-Si:H) layers are deposited by Plasma-Enhanced Chemical Vapor Deposition (PECVD), which includes the flammable and toxic boron/phosphorous gas precursors. Due to this, carrier selective TMO is gaining popularity as analternative risk-free material in place of conventional a-Si:H. In this work hole selective materials such as MoOx, WOx and V2O5has been investigated. Recently MoOx, WOx & V2O5 hetero-structures showed conversion efficiency of 22.5%, 12.6% & 15.7% respectively at temperature below 200°C. In this work a concise review on few important aspects of the hole selective material solar cell such as historical developments, device structure, fabrication, factors effecting cell performance and dependency on temperature has been reported.
Simpy Sanyal,김태용,전성호,이윤정,이준신,최인혁,손주암,구자빈 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.6
Corrosion of porcelain insulators has become a consequential threat to the secure and steady performance of power utilities. The losses due to corrosion have been calculated to be approximately 2–5% of the gross national product of any country. Under the infl uence of various contaminated environment, space between lower surface of iron cap and porcelain surface bridged by water which supports corrosion in iron cap and pin because of electrolytic process. Investigations validate corrosion found within metal part of insulators can worsen the bond between metal part and other accessories surrounding it and degrade its electrical and mechanical characteristics. These issues can be suppressed partially by utilizing various approaches such as washing and greasing of insulators, utilizing corrosion resistant metals and nonmetallic pins, zinc sleeve concept and U-shaped zinc ring etc. This paper highlights principle of corrosion mechanism especially focusing on corrosion occurs in metal part of insulators, causes of corrosion, dominance of pin and iron cap corrosion on mechanical and electrical characteristics of insulators. Furthermore, various approaches for suppression of corrosion in metal part of suspension insulators have been reviewed.
Deterioration of Porcelain Insulators Utilized in Overhead Transmission Lines: A Review
Simpy Sanyal,Fawad Aslam,김태용,전성호,이윤정,이준신,최인혁,손주암,구자빈 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.1
Reliability of a power system is generally designated as a measure of the ability of the system to provide customers with adequate and constant supply. Power system failure have adverse eff ects and become a great concern for important large scale industries in South Korea such as semiconductors, steel and chemicals which require a high quality, stable power supply. In South Korea, nearly 80% of transmission system failures are caused by either natural eventualities such as lightning strikes or failure of insulators. Ageing assets pose signifi cant challenges for utilities. Moisture with high temperature, fl uctuation in temperature, contamination and electric stress accelerates aging in suspension insulators. The primary goal for the utility is to utilize the full life of an asset, but ageing increases the probability of deterioration and failure of equipment. The average age of vital assets, is estimated to be more than 35 years. In South Korea near about 1,223,538 porcelain insulators are reported to be in functional state. Among them only 65.19% of insulators are reported to be in operative state over 35 years. Insulators demand only 5–8% of installation costs. However, it demands more than 50% of maintenance costs. Thus, deterioration of insulator enhances capital expenditure and decrease returns on the asset base. Therefore, insulators should possess excellentelectrical aging resistance to prevent deterioration of insulators. Korea Electric Power Corporation (KEPCO), largest power generation and distribution utility in South Korea utilize porcelain for almost all suspension insulators employed in transmission lines. Porcelain insulators are usually employed in transmission system as they are cost-effective and possess near about 30 to 60 years of lifespan. Lifetime evaluation of porcelain insulators in overhead transmission line is absolutely challenging, owing to aging process. This work highlights investigation of various failures of suspension type porcelain insulators, infl uencing factors responsible for degradation in lifetime and deterioration of suspension type insulators, various laboratory test methods available for evaluation of insulators employed in overhead transmission lines.
Influence of Electrolytic and Crevice Corrosion on Mechanical Resistance of Porcelain Insulators
Matheus Rabelo,Simpy Sanyal,Taeyong Kim,Ju-Am Son,In-Hyuk Choi,Junsin Yi 한국신재생에너지학회 2021 한국신재생에너지학회 학술대회논문집 Vol.2021 No.7
Porcelain insulators are widely used in transmission lines; however, their durability and considerable overall maintenance cost have become problems over the years. In this work, porcelain insulators were collected from various locations in South Korea and classified according to their length of service. Mechanical and electrical load tests were performed, and the failure load and damaged region were recorded for each specimen. The fast degradation of the pin in porcelain insulators exceeding 50 years in operation was notable because there was no pin breakage among the samples in service for less than 50 years. Moreover, the failure of 73.68% of all porcelain insulators in service for 54 years occurred in the pin. The average failure load of these samples was 14% lower than that of samples in use for 45 years. To confirm the pin’s deterioration mechanism over time, a mechanical analysis of the reduction in the pin cross-section was performed using the finite element analysis method. Accordingly, a novel degradation mechanism is proposed in this study. Previous studies that focused on the critical areas of the porcelain insulator found that the exposed pin side was easily damaged by the external load. The current findings revealing an unfamiliar porcelain deterioration mechanism may aid in the formulation of a better design to mitigate the problems described above.
A Brief Study on the Fabrication of III-V/Si Based Tandem Solar Cells
Swagata Panchanan,DUTTA SUBHAJIT,Kumar Mallem,Simpy Sanyal,박진주,주민규,조영현,조은철,이준신 한국태양광발전학회 2018 Current Photovoltaic Research Vol.6 No.4
Silicon (Si) solar cells are the most successful technology which are ruling the present photovoltaic (PV) market. In that essence, multijunction (MJ) solar cells provided a new path to improve the state-of-art efficiencies. There are so many hurdles to grow the MJ III-V materials on Si substrate as Si with other materials often demands similar qualities, so it is needed to realize the prospective of Si tandem solar cells. However, Si tandem solar cells with MJ III-V materials have shown the maximum efficiency of 30 %. This work reviews the development of the III-V/Si solar cells with the synopsis of various growth mechanisms i.e hetero-epitaxy, wafer bonding and mechanical stacking of III-V materials on Si substrate. Theoretical approaches to design efficient tandem cell with an analysis of state-of-art silicon solar cells, sensitivity, difficulties and their probable solutions are discussed in this work. An analytical model which yields the practical efficiency values to design the high efficiency III-V/Si solar cells is described briefly.