Electrical Transmission Cables Research Articles

Directional motion of water droplets enhances anti-icing failure of structural superhydrophobic surfaces

Preventing ice formation on solid surfaces is a crucial concern in various applications, such as aircraft de-icing and protecting electrical transmission cables. One approach to combat ice or frost formation involves the fabrication of superhydrophobic surfaces with micro- or nanostructures. However, some research suggests that the effectiveness of these superhydrophobic surfaces in preventing ice formation may be compromised under conditions of high humidity and low temperatures. Many researchers attribute the resistance of the wetting transition from the Cassie-Baxter state to the Wenzel state on superhydrophobic surfaces to Laplace pressure difference. However, according to molecular dynamics simulations and physical experiments, we find that the impact of Laplace pressure difference depends on the relative size of water droplets and air pockets on the structure. If the size of water droplets is smaller than the characteristic length of the air pockets, directional motion due to Laplace pressure difference and van der Waals force leads to water droplet aggregation and accelerates the ice formation and failure of anti-icing measures. Therefore, our research offers significant insights into the mechanical mechanisms that contribute to the failure of anti-icing techniques on structural superhydrophobic surfaces. This understanding is critical for the design of effective anti-icing or icephobic surfaces.

Drying of cable backfill by vapour diffusion balanced by capillary water suction: a laboratory experiment with altered groundwater levels

The performance of underground infrastructures, such as an electrical transmission cable, is strongly affected by transmission-induced high temperatures, which have an impact on the properties of the cable and the electric load. Therefore, it is essential to determine if a high load will cause a dry out of a sandy thermal backfill close to the cable. This paper aims at describing processes and establishing criteria for when a dry out can occur. Processes that are addressed are e.g., vapour diffusion and capillary water transport. Criteria of interest are e.g., groundwater levels and capillarity of soil. A new pilot laboratory experiment, with varying groundwater levels, was developed to investigate the dry out of the cable sand in close proximity to an operating cable. The experimental results show that a thermal backfill can withstand a dry out, at a high current load in a cable, if there is a capillary contact to a groundwater level 2 m below the backfill material.

Kinematics of platform stabilization using a 3-PRS parallel manipulator

In this paper, a 3-PRS (prismatic, revolute, and spherical) parallel manipulator for platform stabilization is designed. The main purpose of this device is to stabilize visual equipment, which is placed on top of a car to inspect electrical transmission cables, as part of routine maintenance. Due to the bulky and heavy infrared cameras used during inspections, a stabilizer platform has been designed to handle the weight of camera equipment up to 10 kg. This device consists of two major mechanisms. The first mechanism is able to adjust the angle of the camera. Thus, the user can focus the camera along the electric transmission lines. The second mechanism is stabilization. The mechanism serves to stabilize the orientation and position of the camera in the roll, pitch, and heave directions. To test the performance of the stabilization mechanism, the device is fed with the known value of the angle with regard to the input. As such, the device is trying to compensate for the change in angle. The results show that the errors between the input angles and compensated angles are in the range of 0.4–3%. Errors are seen to be within an acceptable range. It is significant that the resultant errors do not affect the orientation of the camera.

Ultrastrong Carbon Nanotubes–Copper Core–Shell Wires with Enhanced Electrical and Thermal Conductivities as High-Performance Power Transmission Cables

Demands for high-performance electrical power transmission cables continue to rise, especially for offshore power transmission, electric vehicles, portable electronics, and deployable military applications. Carbon nanotubes (CNTs)-Copper (Cu) core-shell wire is regarded as one of the best candidate material systems for transmitting electricity and thermal energy. In this study, a facile and robust approach was developed to enhance the CNT-Cu interfacial interactions. This approach consists of a substrate-enhanced electroless deposition step for Cu pre-seeding and thiol functionalization. Benefiting from the thiol-activated CNT surface and Cu seed deposit, the CNTs-Cu core-shell wire forms a densely packed Cu shell with a void-free CNT-Cu interface. Consequently, the CNTs-Cu core-shell wire possesses (1) superior specific strength (eightfold stronger), (2) 30% higher specific conductivity, (3) 120% higher specific ampacity, and (4) an impressive 110% higher thermal conductivity compared with pure Cu wires. Moreover, this composite wire still maintains its structural integrity and electrical properties over 600 cycles of the fatigue bending test, rendering this system an excellent candidate for high-performance electrical cable and conductor applications.

A photogrammetric solution for measurement of power lines sag via integration of image and accelerometer data of a smartphone

Measuring the sag of electrical power transmission cables is an index for sensing their internal tension and safety. In this paper, a simple photogrammetric solution is proposed to measure them which only requires an image taken by a smartphone equipped with an internal accelerometer. In this method, a modified version of the well-known co-linearity condition is proposed and the 3D locus of cables has been modeled with a parabola equation. Accelerometer measurements are used to prevent the ill-posed conditions of unknowns’ estimation and are also contributed to generating the control data for the estimation of unknowns. The distance between the supporting points of cables is the only required control information for this method. The proposed solution, while simple, significantly has reduced the risks and costs of measuring the cable sags. On average, the obtained results indicate a relative accuracy of 2.6% in the estimation of the sags of cables.

OBSERVATIONAL STUDY OF ELECTRICAL BURN CASES AT A TERTIARY CARE CENTRE IN CENTRAL INDIA

ABSTRACT Background :- Electricity has become an integral part of our lives in today’s era of technology . Electrical burn injuries comprise a low fraction of the entire burn admissions but they are potentially a mutilating type. The aim of this study is to know the demographic pattern of electric burn cases in our region, along with the morbidity and management of electric burn injuries in a tertiary centre of central india. Methods :- This was a retrospective study conducted by reviewing the medical records of all burn admissions from July 2017 to June 2019 and data was analysed for demographic characteristics and outcomes and patterns of electric burn injury Results :- Out of 26 total electric burn cases, maximum cases (65.38%) were adult above 20 years of age. Having male to female ratio of 3.5:1 , most of them belonged to rural place. (84.61%) Of all the cases studied,maximum were of High Voltage (>1000 V) Injury 61.53%, encountered mostly in outdoors and at work places.Hand (50%) was the commonest part to be affected. 61.53% of all affected individuals had to undergo a surgical intervention of which 50% underwent debridement, with a mean hospital stay of 27.08+/-12.09 days for high voltage injuries Conclusions:- Electrical injuries are generally preventable. This epidemiological study on the patients of electric burn suggests that most of the human and economic losses caused by the accidents leading to electric burn injuries were young males, hailing from rural areas and suffered high voltage burns, which could have been prevented by implementation of safety measures at work place. Hence general education regarding safety measures while using the electricity should be given in primary schools itself. High voltage electrical transmission cables should be placed underground.

Performance-Related Assessment of the Potential Use of Sawing Sludge in Cementitious Fluidized Thermal Backfills

The management of sawing sludge originated from cutting operations of ornamental stones represents a challenging task as a consequence of its peculiar composition that includes non-negligible amounts of heavy metals resulting from the wear and tear of cutting tools. The aim of the research work presented in this paper was to investigate the feasibility of using these by-products as supplementary constituents of cementitious mixtures employed for the formation of Fluidized Thermal Backfills (FTB). These mixtures are designed and produced for filling operations in pavement subgrades in which high-voltage electrical transmission cables are buried for protection purposes. Two different types of sawing sludge were thoroughly analyzed from a physical and chemical point of view and thereafter employed for the laboratory production of four FTB mixtures. Then, these were subjected to thermal, mechanical, and environmental tests in order to verify their suitability for their intended use. All investigated FTB mixtures exhibited a satisfactory and stable thermal conductivity, and they also displayed enhanced stiffness properties in comparison to standard subgrade and sub-base materials. Controversial results were obtained with respect to environmental properties resulting from leaching tests, thus suggesting that further investigations are needed before any full-scale application can take place.

Detailed atmospheric ice accretion surface measurement using micro‐computed tomography

AbstractSurfaces exposed to atmospheric cold temperature and humid environments are prone to ice accretion. Airplanes, electrical power transmission cables, and wind turbines are typical examples for which icing has to be considered. The measurement of the resulting ice shapes is a challenging process. While macroscopic characteristics of the ice geometry can be observed using photography and optical scanning techniques, microscopic measurements are difficult to conduct because grooved surface partially occludes the geometry of chasms. To overcome this optical inaccessibility, we propose a method to carry out detailed high‐resolution measurements of the accretion surface with micro‐computed tomography. This approach provides a unique visualization of the empty spaces in the feather region. The information obtained by this technique can improve the understanding of ice accretion physics and its computational modeling.

Separation, size reduction, and processing of XLPE from electrical transmission and distribution cable

AbstractThe recycling of power transmission cable insulated with crosslinked PE (XLPE) was investigated by using different methods of separation and reprocessing. Separation was attempted by thermo‐chemical, thermo‐mechanical and microwave‐mechanical means, the latter being the most successful. A mechanism encompassing all of these was formulated. Compression molding, extrusion, and injection molding with and without preheating of the material were also investigated. It was found that by preheating the XLPE and injection molding under high injection pressure, the neat XLPE could be formed into shapes with tensile strengths equal to that of the original insulation. In view of available observations, possible mechanisms for the flow and reconsolidation of XLPE crumb are proposed and discussed.

Structure of Ice Layers on Electrical Transmission Cables with Raman Microprobe Spectroscopy

An icing chamber employing a closed-cycle helium cryostat has been fabricated for Raman microprobe spectroscopy of the icing on electrical transmission cable samples. A thick layer of ice deposited on a cable sample at low temperature (30 K) evaporates gradually under vacuum by increasing the temperature at intervals of 10 K up to 180 K. The Raman spectra of the gradually thinning ice layer obtained in the O-H stretching region reveals the layer-by-layer structure of ice. The study suggests that the structure of the initial ice changes from low-density amorphous ice at low temperatures to high-defect-density polycrystalline ice at higher temperatures. This observation, made for the first time on electrical transmission cable samples, is consistent with the observed phase diagram of bulk amorphous ice.

Legal, institutional and financial aspects of an inter-island electrical transmission cable

The Hawaii Deep Water Electrical Transmission Cable Demonstration Program (HDWC Program) was initiated in October 1981 by the State and Federal Governments as a research, development and demonstration program. Its purpose is to explore the technical, environmental and financial dimensions of a deep water electric energy transmission cable system which would deliver electric energy from the abundant renewable alternate energy resources (especially the geothermal resources in the Puna area) on Hawaii to Oahu, where the State's largest electric demand exists. If such a cable system is developed, it could result in reducing the amounts of high-cost imported fuel oil presently used to produce electric energy and power. While the HDWC Program has to date focused on the scientific, technological and engineering aspects of a deep water cable, there has been a continuing recognition of the need for a preliminary analysis of the legal, institutional and financing aspects of a cable system. The installation and operation of a cable system would occur within a legal and regulatory framework requiring, among other things, obtaining all required Federal, State and County permits and approvals. Moreover, an appropriate organizational structure must be created to undertake the initial development activities and subsequent installation and operation of a cable system. Finally, the cost of a cable system is currently projected to be some $334-400 million (1982 dollars). This preliminary study reviews and analyzes the international, national, state and local laws, rules and regulations which would apply to a cable system; analyzes the laws, rules and regulations which affect the capital accumulation, ownership and operation of a cable system; and reviews the financial considerations, approaches and specific sources of capital which would affect the financing of a cable system. However, the development of a commercial cable system cannot be examined in isolation, particularly because the costs involved and the possible financing approaches to fund those costs depend upon ensuring that a cable system will be able adequately to assure the generation of sufficient revenues to satisfy the requirements of the financing and provide a reasonably reliable supply of electric energy to Oahu. Since the purpose of a commercial cable system would be to transmit electric energy generated from the renewable alternate energy resources (especially the geothermal resources in Puna) on Hawaii to Oahu, it would not be financially feasible to raise the required financing for a cable system and then actually to install the cable without the coordinated development of the

Hawaii's geothermal and deep water cable programs

Hawaii's dependence on imported fuel oil for over 90% of its energy needs can be minimized by exploitation of the State's abundant indigenous energy resources. Geothermal power offers the best prospect for providing a significant baseload alternative to oil-fired electrical energy. However, the largest resource is on the Island of Hawaii, which is separated by a substantial distance and extreme ocean depths from the State's load center on Oahu. No high voltage direct current electrical transmission cable has ever been installed under these conditions. This paper presents an overview of geothermal development in Hawaii and some details of the ongoing Hawaii deep water cable feasibility program to provide the necessary energy bridge.

Coupled Heat and Water Flows Around Buried Cables

Theoretical and experimental studies of heat flow and moisture movement under thermal gradients are described with particular emphasis on flows around buried electrical transmission cables. A one-dimensional finite difference computer program for analysis of coupled heat and water flows in layered systems based on the Philip and DeVries theory is developed. Theoretical analysis indicate that the most important parameters affecting rate and amount of moisture migration away from buried heat sources are the sources temperature and the soil type. A field test was conducted to evaluate the heat and moisture flow predictive methods. The results showed that water content predictions using the coupled flow computer program match poorly with the actual values, and that predicted values are very sensitive to the soil properties used. A finite element two-dimensional computer program is used to predict the variation of temperature distributions around the buried cable with time after initiation of cable heating. The results show very good agreement between measured and predicted temperature contours.