Advancement of TDR Technique for Locating Power Cable Insulation Degradation

This paper discusses the advancement of time domain reflectometry (TDR) technique for locating degradation in power cable insulation with and without jointing. TDR technique is commonly used for localizing processes in various fields. It applies the concept of radar where a signal propagates through a medium will be reflected when there is an impedance mismatch. However, the application of TDR technique in power cable is still limited and its potential to pinpoint the exact location of degradation in power cables is to be ascertained. This study conducts experiments to investigate the potential of this technique in pinpointing the location of degradation in power cable with and without jointing. Experiments are conducted on un-degraded cable without any joint and followed by cable with jointing up to 2 cable joints. For experiments with jointing, the un-degraded cable is sectionalized into 2 parts, and one of the sections is replaced by a degraded cable. Experiments are repeated by sectionalizing the un-degraded cable into 3 parts, and each section is replaced with a degraded cable up to 2 sections. TDR results from all experiments are compiled and then analyzed. The results obtained from this study have proven that TDR technique is capable of identifying the degradation along a cable and at the same time pinpointing the exact location of degraded cable section

The impact of substation grounding grid design parameters in non-homogenous soil to the grid safety threshold parameters

It is important to ensure that a grounding system is designed with a low magnitude of earth resistance, so the protection system can divert the large fault current to earth effectively. The performances and protection level of a grounding system need to be acknowledged as the condition of soil structure changes with different soil characteristics. At present, there is a lack of systematic guide or standards for grounding grid designs that consider non-uniform soil and its impact on the grounding systems. By computing the grid safety threshold parameters consisting of the grid impedance, step, and touch voltages, a comparison has been made between uniform soil and two-layer soil models. Where the competence and level of safety of the grounding systems depend on the soil attributes, the significant impact of various soil conditions is seen. The evaluations on performance and safety assessment in two-layer soil conditions hold the novelty and originality as there is no such comparison and discussion have been made to date. These comparisons would help in forecasting the behavior and safety of the grounding system in various soil environments, which would provide engineers with additional expertise to design an effective and secure grounding system. This research would contribute to the existing body of knowledge by differentiating and predicting the performance of a grounding system when the characteristics of the soil differ significantly from uniform soil as most of the standards and guidelines only consider uniform soil while designing a grounding system, owing to its complexity at the site

Effect of non-homogeneous soil characteristics on substation grounding-grid performances: a review

Designing an effective grounding system for AC substations needs predetermination of ground resistance and ground potential distribution caused by fault current’s presence in the ground. Therefore, it is necessary to have a suitable grounding grid structure in the soil properties in which the grid is buried. Though the soil composition where the grounding grid is located is typically non-homogeneous, the soil is often presumed to be homogeneous due to the complexities of grounding system analysis in non-homogeneous soil. This assumption will lead to inaccuracies in the computation of ground resistance and ground potentials. Although extensive research has been done on non-homogeneous soil structure, comprehensive literature on grounding system performance in non-homogeneous soil is yet to be reviewed. Thus, this paper reviews the effect of non-homogeneous soil on the grounding system, with different soil characteristics in horizontal and vertical two-layer soil structure and the horizontal three-layer soil structure. In addition, the effect of design parameters on the grounding performance in non-homogeneous soil conditions for non-transient fault conditions is also studied. The significance of this study is that it provides a comprehensive review of grounding performance as grounding design changes and their effects as soil layers and their corresponding features change. This knowledge will be useful in developing safe grounding designs in non-homogeneous soil

An ergonomic perspective of user need on physio-treadmill (phymill) criteria: knowledge and awareness of cerebral palsy among future parents

Cerebral palsy (CP) is the most common childhood disability. This study focused to explore the future parents’ perspective on the Physio-Treadmill (PhyMill) for the kid with CP, particularly how ergonomics influences the product. The study was carried out by a quantitative survey and involves 55 participants. The participants have answered a self-administered which consists of general information, knowledge awareness on cerebral palsy, product criteria and opinions. The result shows about 55% of participants have a poor level of awareness and 69% of participants have zero knowledge of CP treatment. However, based on the product criteria, most of the participants agreed, the present PhyMill shows well in functionality. Hence, this study emphasized the lack of awareness and knowledge of the disease and treatment among future parents. Besides, the PhyMill need to improve from the potential user recommendation as ergonomics consideration on medical devices

The Treatment Impact of Partial Body Weight Supported Treadmill (PBWST) on Cerebral Palsy Kid Using Physio-Treadmill (PhyMill): A Case Study

Cerebral Palsy (CP) prevalence has remained stable in the global population over the last few years. This case study aims to examine the impact of the Partial Body Weight Supported Treadmill (PBWST) on gait control in kids with cerebral palsy. Kids with CP completed a gait training protocol two-session between two weeks’ intervals. Outcome measures included a Berg balancing scale, Dynamic gait index, Katz index of independence in activities of daily living, and several steps. The individual results indicated there were improvements in balance, dynamic gait, and step count. After the second session, the number of steps improved. The step length of the second session is better. There were more active movements during the second session. Additional research is needed to determine the treatment parameters and the long-term effects of PBWST on gait performance in CP children

Ergonomics study on visual contribution of postural stability using Physio-Treadmill (PhyMill) for kid with cerebral

Cerebral Palsy (CP) is a movement, muscle tone, and or posture congenital disorder. The partial body weight supported with treadmill training (PBWSTT) is one option successfully used to improve gait performance in children with CP. The treadmill exercise is used for repetitive activities. The emphasis is on enhancing the strength of the lower extremity, speed of walking, or endurance. The patient was a 6-year-old kid who was diagnosed with CP with GMFCS Level II. Five conditions with visual and angle diagram conflicts were selected to observe on balance control in the study participants. The use of a harness is for more control of posture and stability. The best posture during sitting on the harness, standing, and walking on the PhyMill were discussed in this paper. The posture of the body should correspond to the ability and correct angle of movement of the foot shown in the angle diagram. It also allows for the exploration of factors that limit the adaptability of gait in person with CP. Backward walking can reinforce rectal femoris and anterior tibialis in cerebral palsy treadmill training

Low-temperature nitrogen doping of nanocrystalline graphene films with tunable Pyridinic-N and Pyrrolic-N by cold-wall plasma-assisted chemical vapor deposition

We report a viable method to produce nanocrystalline graphene films on polycrystalline nickel (Ni) with enhanced N doping at low temperatures by a cold-wall plasma-assisted chemical vapor deposition (CVD) method. The growth of nanocrystalline graphene films was carried out in a benzene/ammonia/argon (C6H6/NH3/Ar) system, in which the temperature of the substrate heated by Joule heating can be further lowered to 100 °C to achieve a low sheet resistance of 3.3 k? sq-1 at a high optical transmittance of 97.2%. The morphological, structural, and electrical properties and the chemical compositions of the obtained N-doped nanocrystalline graphene films can be tailored by controlling the growth parameters. An increase in the concentration of atomic N from 1.42 to 11.28 atomic percent (at.%) is expected due to the synergetic effects of a high NH3/Ar ratio and plasma power. The possible growth mechanism of nanocrystalline graphene films is also discussed to understand the basic chemical reactions that occur at such low temperatures with the presence of plasma as well as the formation of pyridinic-N- and pyrrolic-N-dominated nanocrystalline graphene. The realization of nanocrystalline graphene films with enhanced N doping at 100 °C may open great potential in developing future transparent nanodevices

Development of Physiotherapy-Treadmill (PhyMill) as Rehabilitation Technology Tools for Kid with Cerebral Palsy

Main problems with the motor function for Cerebral Palsy (CP) kids are delayed or arrested on motor development. Therapeutics typically emphasize sound-inhibitory exercises, balance training, and preparatory tasks while walking, sitting, and standing to enhance the functioning of children with CP. The treadmill training is used for repeated tasks-specific walking. The focus is to increase the strength of lower extremity, walking speed, or endurance. In this study, we developed the physio-treadmill device for CP kids called PhyMill. This PhyMill is mainly constructed from the aluminum profile connected to connector made by polylactic acid (PLA) material equipped with an automatic control system. The height of the device can be adjusted according to the user’s height. PhyMill offers three operating modes, the first one allowing you to control the movement of the patient forward and backward. The height of the device can be adjusted automatically according to the user’s height is the second mode. The third mode is a special display screen to attracts the attention of the patient. The protection when using this device is also highlighted by supporting the user with an adjustable harness. Treadmill exercise for non-ambulatory children with CP as rehabilitation technology tools is a promising technique for the treatment of partial body weight support

The measurement and modelling of electroluminescence in high voltage polymeric cable insulation materials

Since space charge plays a significant role in long-term electrical degradation of polymeric insulation in high voltage cables, there is growing interest in the measurement of the energy dissipation of mobile and trapped charges in the dielectric molecules. The dissipation process is associated with the emission of visible photons, a process known as electroluminescence (EL) and can be used, potentially, as an indicator for the initiation of electrical ageing of insulation. This thesis is based on an investigation into the occurrence of EL in dielectric materials as a result of applying high ac stresses. The phenomenon has been observed and analyzed for different types of thin polymeric films using a charge coupled device (CCD) detection system. This unique experimental setup enables a range of measurements to be performed including the imaging of EL, its temporal behaviour, spectral analysis and phase-resolved measurements using the same detector. The effects of several factors such as the types of material under study and local gas environment have been assessed based on the results obtained. Previously, different research groups have monitored the occurrence of EL under ac conditions by applying a sinusoidal electric field across the polymer but in this project, the emission is also examined under the influence of triangular and square voltage waveforms, together with their asymmetrical counterparts. In addition to this, a dynamic bipolar charge recombination model has been developed in order to simulate studies of EL under an alternating field. By comparing experimental results with the simulation, the theories relating to the processes responsible for the occurrence of EL have been evaluated and a good agreement was found between the simulation and experimental results.</p

The measurement and modelling of electroluminescence in high voltage polymeric cable insulation materials

Since space charge plays a significant role in long-term electrical degradation of polymeric insulation in high voltage cables, there is growing interest in the measurement of the energy dissipation of mobile and trapped charges in the dielectric molecules. The dissipation process is associated with the emission of visible photons, a process known as electroluminescence (EL) and can be used, potentially, as an indicator for the inhibition of electrical ageing of insulation. This thesis is based on an investigation into the occurrence of EL in dielectric materials as a result of applying high ac stresses. The phenomenon has been observed and analyzed for different types of thin polymeric films using a charge coupled device (CCD) detection system. This unique experimental setup enables a range of measurements to be performed including the imaging of EL, its temporal behaviour, spectral analysis and phase-resolved measurements using the same detector. The effects of several factors such as the types of material under study and local gas environment have been assessed based on the results obtained. Previously, different research groups have monitored the occurrence of EL under ac conditions by applying a sinusoidal electric field across the polymer but in this project, the emission is also examined under the influence of triangular and square voltage waveforms, together with their asymmetrical counterparts. In addition to this, a dynamic bipolar charge recombination model has been developed in order to simulate studies of EL under an alternating field. By comparing experimental results with the stimulation, the theories relating to the processes responsible for the occurrence of EL have been evaluated and a good agreement was found between the simulation and experimental results.EThOS - Electronic Theses Online ServiceGBUnited Kingdo