Clearance Requirements Research Articles

The National Electrical Safety Code, powerline clearances, and wildfires

AbstractThe provisions of the National Electrical Safety Code (NESC) have a long, but undocumented history. They are the primary means by which Public Utilities Commission agencies in various States in the United States enforce requirements for electrical clearances pertinent to high‐voltage powerlines. Examination of the NESC provisions for clearances between grounded guy wires and distribution phase conductors in the context of the Woolsey Fire indicates a comprehensive lack of realism in the Code provisions. While they may be entirely sufficient to prevent sparkover under normal operating conditions, they are wholly insufficient to cope with even modest adverse events. The profession should consider explicitly assessing factors beyond sparkover that affect the adequacy of clearance requirements. The provisions of the NESC (and California's parallel General Order No. 95) should be systematically reexamined in order to ensure that safety regulations can cope with adverse events that are serious, but not extreme. Since the vast majority of the electrical power network is aging and not new construction, a scheme should be developed to establish priorities for upgrading existing facilities at the highest risk of failure.

Efficient Railway Gauge Conversion with Tunnel reconstruction

The modernization of railway networks constructed during the colonial era requires the conversion of railway gauges from the metric to the standard gauge, as well as the expansion from single-track operation to a dual-track operation in order to accommodate railway infrastructures with the traffic growth. Existing critical infrastructures such as bridges and tunnels in the existing network will also require appropriate reconstruction measures since minimum clearance requirements associated with the standard gauge are subjected to new rolling stock and maintenance facilities. The present work presents an optimal procedure to solve efficiently the problem of a tunnel reconstruction during track conversion while maintaining trains circulation during the transition period from metric to standard gauge with less traffic interruption. From a multi-criteria comparison scheme we examine different options ranging from enlarging the existing tunnel to constructing an adjacent new standard gauge dual-track tunnel with the construction of an adjacent standard gauge single-track tunnel as a neutral choice. Results show that enlarging the existing tunnel under a sustained traffic, is both technically feasible and economically viable.

Influence of Genetic Polymorphisms in CYP3A5, CYP3A4, and MDR1 on Tacrolimus Metabolism after kidney transplantation

Kidney transplantation stands as the ultimate recourse for restoring vital organ functions, particularly in cases of end-stage kidney disease where alternative treatments, such as dialysis, prove less effective. With over 102,000 kidney transplants conducted globally in 2022, the demand for organ transplantation is ever-increasing, fueled by a rising incidence of end-stage renal disease attributed to causes like diabetes and hypertension.<br /> Despite significant advancements in kidney transplantation, immunosuppressive therapy remains crucial to preventing graft rejection. Tacrolimus (TAC), a calcineurin inhibitor, plays a pivotal role in this regard. Discovered in 1984, TAC inhibits T-lymphocyte activation, preventing acute rejection by disrupting the transcription of crucial genes involved in early T-cell activation. However, the use of TAC is not without challenges. The drug exhibits serious side effects, a narrow therapeutic index, and unpredictable pharmacokinetics. Therapeutic drug monitoring (TDM) becomes imperative in daily practice to maintain TAC blood concentrations within the therapeutic range. This literature review delves into the genetic aspects influencing TAC metabolism, focusing on key polymorphisms in CYP3A5, CYP3A4, and ABCB1 genes. Genetic variations in CYP3A5, a major enzyme in TAC metabolism, impact enzyme activity, necessitating personalized dosing strategies. CYP3A4 polymorphisms, especially CYP3A4*22, demonstrate associations with altered TAC clearance and dose requirements. The ABCB1 gene, encoding P-glycoprotein, another player in TAC pharmacokinetics, also exhibits polymorphisms influencing drug absorption and distribution. The ABCB1 3435C>T variant, in particular, shows potential implications on Tacrolimus bioavailability. Understanding these genetic variations aids in the development of personalized dosing regimens. Studies suggest that tailoring TAC doses based on CYP3A5 genotypes significantly improves the proportion of patients achieving therapeutic concentrations. Additionally, incorporating genetic information, particularly CYP3A4*22, into dosing strategies enhances the precision of TAC therapy, reducing the risk of adverse effects.

ANALYSIS OF THE PERFORMANCE OF A JOINT THAT COMBINES HIGH-STRENGTH BOLTS AND WELDING

In steel constructions, sometimes, it is necessary to combine bolts and welds in a single joint. While some design provisions for these combination joints appear in current standards, there have been no design rules generally verified by physical tests. In addition, the rules appear illogical in some cases, possibly leading to unconservative designs. The need for a combined joint in steel structures can arise for several reasons. For example, load requirements for an existing bolted joint may change, necessitating the joint redesign. As a result of bolt clearance requirements or limitations due to the existing joint plate size, there may not be sufficient space to add more bolts. Also, drilling a new bolthole in the field may not be possible because of space restrictions. For this situation, adding welds to the joint is the only practical option to give the joint the necessary increase in load resistance. The need for a combination joint may also arise in new construction. Another situation often requiring a combination joint is repairing a riveted joint. The assumption that the ultimate strength of a connection is the sum of the ultimate strength of each mechanical fastening element present in the connection is an unconservative approach to the design of the connection. In contrast, only accounting for the ultimate strength of one of the individual types of mechanical fastening elements in a combination joint is a very conservative approach. In the design of steel structures, it may be necessary to use a combined joint in which bolts and welds take up the force flow. Guidelines for the design of such a combined joint are available in the current DBN B.2.6-198:2014 ‘Steel structures. Design standards’. However, there are no practical examples and recommendations for calculating this type of joint in the scientific and technical literature. This article is devoted to studying the combined joint to improve understanding of the nature of its operation. The authors achieved the goal by numerical modelling of combined joints. Numerical experiments have shown that the welds’ orientation and the bearing capacity of bolts are two key factors to consider when determining the proportion of force acting on welds and bolts. Keywords: high-strength bolt, welds, combined joint, stress-strain state.

Fault Ride-Through Method for Interline Power Flow Controller Based on DC Current Limiter

The interline power flow controller (IPFC) based on a modular multilevel converter with a half-bridge configuration can control the active and reactive power flows of multiple alternating current (AC) lines. However, it forms a multiterminal system on the direct current (DC) side, which leads to DC faults. To reduce the protection and clearance requirements on the DC side of IPFCs, this paper proposes a hybrid current limiter topology suitable for generating a DC-side fault ride-through scheme. The current limiter employs a low-loss branch in steady-state conditions; when the fault occurs, a commutation capacitor and controllable power electronic devices are used to transfer the fault current to the current-limiting branch. To clarify the operating principles of the current limiter, the working states of each stage and electrical stress of each device are analyzed. Different components with varying limiter parameters are also discussed, and optimal parameters to achieve the best limitation effect are discussed. PSCAD simulations show that the proposed limiter can limit the overcurrent effectively, and DC-side fault clearance can be achieved easily with this fault ride-through strategy.

The Position of the Principle of Legality vs the Principle of Opportunity in the Accemination of the Prosecutor's Demands in the Replic Agenda (Valencya Case Study at the Karawang State Attorney)

Withdrawing criminal charges against Valencya during a trial's replication stage has generated debate, seemingly balancing the principles of legality and opportunity. This issue is significant because the Prosecutor in the Valencya Case has effectively assumed the role of Legal Advisor. This study presents a descriptive analysis of normative research within the criminal procedure system. By detailing the placement of legal charges in the Valencya case, a thorough analysis is conducted regarding the Public Prosecutor's authority in determining the legality and the discretion to discontinue prosecution. The Principle of Opportunity justifies discontinuation efforts in charge acquisition, even when clearance requirements are conducted in the replica agenda. While prioritizing legal interests to achieve justice for victims, the principle of legality can be waived, aligning with the concept of restorative justice in the Prosecutor's Office agenda.

Tri-arm MIMO array antenna pair for mobile phone applications

Abstract An 8 × 8 tri-arm multiple-input multiple-output (MIMO) array using novel even–odd mode decouplers is presented. To decouple the directly connected driven ports on the tri-arm antenna pair, a T-shaped stub working as an even-mode decoupler and a narrow strip working as an odd-mode decoupler are elaborately introduced. Therefore, the even-mode and odd-mode impedances cross with the antenna input impedance, and a deep coupling zero is achieved at this cross frequency. Finally, the proposed 8 × 8 MIMO array was developed, fabricated, and measured for further performance verification. The measured results show that the proposed array can have a wide isolation bandwidth of 17.2 % with a compact size of 0.44λ 0 × 0.08λ 0 and zero clearance requirement on the ground plane. The diversity performances are also investigated with the measured worst envelope correlation coefficient less than 0.05.

Formation‐Aware Planning and Navigation with Corridor Shortest Path Maps

AbstractThe need to plan motions for agents with variable shape constraints such as under different formations appears in several virtual and real‐world applications of autonomous agents. In this work, we focus on planning and execution of formation‐aware paths for a group of agents traversing a cluttered environment. The proposed planning framework addresses the trade‐off between being able to enforce a preferable formation when traversing the corridors of the environment, versus accepting to switch to alternative formations requiring less clearance in order to utilize narrower corridors that can lead to a shorter overall path to the final destination. At the planning stage, this trade‐off is addressed with a multi‐layer graph annotated with per‐layer navigation costs and formation transition costs, where each layer represents one formation together with its specific clearance requirement. At the navigation stage, we introduce Corridor Shortest Path Maps (CSPMs), which produce a vector field for guiding agents along the solution corridor, ensuring unobstructed in‐formation navigation in cluttered environments, as well as group motion along lengthwise‐optimal paths in the solution corridor. We also present examples of how our multi‐layer planning framework can be applied to other types of multi‐modal planning problems.

Design optimisation of non-axisymmetric exhausts for installed civil aero-engines

Future civil aero-engines are likely to operate with higher bypass-ratios (BPR) than current power-plants to improve propulsive efficiency and reduce specific thrust. This will probably be accompanied by an increase of fan diameter and size of the power plant. Consequently, future configurations are likely to require more close-coupled installations with the airframe due to structural and ground clearance requirements. This tendency may lead to an increase in the adverse installation effects which could be mitigated with non-axisymmetric exhausts. However, due to the prohibitive computational cost, limited regions of the design space have been studied. For this reason, a relatively low-cost design approach for the integrated system is required. The aim of this work is to establish a method to map the non-axisymmetric exhaust design space where the effects of the propulsion system installation are taken into account. The methodology relies on the generation of a design database using inviscid computational fluid dynamics (CFD) methods. This is used to characterise the design space, identify the dominant design parameters and build response surface models for optimisation. The candidate designs that arise from the optimisation are assessed with viscous CFD simulations to assess the aerodynamic mechanisms and performance characteristics. The result is a set of design recommendations for installed configurations with non-axisymmetric exhausts. The method is an enabler for the optimisation of installed propulsion systems and has provided an exhaust design with a 0.7% improvement on net vehicle force relative to an axisymmetric exhaust, for a close coupled configuration where the fan cowl is overlapped with the wing. A reduction in net vehicle force is expected to lead to a similar reduction in cruise fuel burn.

Clear of Clouds? An Assessment of Appealed 91.155 Enforcement Actions

When flying under visual flight rules, pilots must remain clear of clouds. The exact distance varies by airspace class, and this is determined by specific regulatory requirements found within 14 C.F.R. Section 91.155. But there are important questions about the extent to which pilots comply with this regulation, as determining one’s exact distance from clouds is challenging. In this conference paper, we assess the decisions of the National Transportation Safety Board (NTSB) in 20 Federal Aviation Administration (FAA) legal enforcement actions involving a violation of cloud clearance requirements. Among these cases, we examine how 91.155 violations were discovered, the form of sanction imposed by the FAA, the timelines associated with appeals for these cases, and the vote composition of the NTSB in these decisions.

The Effect of Nitazoxanide on the Clinical Outcomes in Patients with COVID-19: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Nitazoxanide, a US Food and Drug Administration-approved antiparasitic agent, was reported to be effective in treating coronavirus disease 2019 (COVID-19). The lack of effective and precise treatments for COVID-19 infection earlier in the pandemic forced us to depend on symptomatic, empirical, and supportive therapy, which overburdened intensive care units and exhausted hospital resources. Therefore, the aim of this systematic review and meta-analysiswas to assess the efficacy and safety of nitazoxanide for COVID-19 treatment. A systematic review and meta-analysis synthesizing relevant randomized controlled trials from six databases (MedRxiv, WOS, SCOPUS, EMBASE, PubMed, and CENTRAL) until 17 May 2022was conducted. Risk ratio (RR) for dichotomous outcomes was usedand data with a 95% confidence interval (CI)arepresented. The protocol was registeredin PROSPERO with ID: CRD42022334658. Six randomized controlled trials with 1412 patientswere included in the analysis. Nitazoxanide was effective in accelerating viral clearance compared with placebo (RR: 1.30 with 95% CI 1.08, 1.56, p = 0.006) and reducing oxygen requirements (RR: 0.48 with 95% CI 0.39, 0.59, p = 0.00001), but we found no difference between nitazoxanide and placebo in improving clinical resolution (RR: 1.01 with 95% CI 0.94, 1.08, p = 0.88), reducing the mortality rate (RR: 0.88 with 95% CI 0.4, 1.91, p = 0.74), and intensive care unit admission (RR: 0.69 with 95% CI 0.43, 1.13, p = 0.14). Moreover, nitazoxanide was as safe as placebo (RR: 0.9 with 95% CI 0.72, 1.12, p = 0.34). Compared with placebo, nitazoxanide was effective in expediting viral clearance and decreasing oxygen requirements. However, there was no difference between nitazoxanide and placebo regarding clinical response, all-cause mortality, and intensive care unit admission. Therefore, more large-scale studies are still needed to ascertain the clinical applicability of nitazoxanide in COVID-19.

Acute Intermittent Peritoneal Dialysis in Critically Ill COVID-19 Patients with Renal Failure: Saviour or Succourer

Background: The COVID-19 pandemic has led to an increase in critically ill patients with renal failure, with many requiring renal replacement therapies. Unfortunately, many of them are too critically ill to tolerate intermittent hemodialysis. In the setting of limited resources, we did bedside acute intermittent peritoneal dialysis for critically ill COVID-19 patients with hemodynamic instability with or without ventilator support admitted to our intensive care unit. Objective: The aim of the study was to determine the outcome of intermittent peritoneal dialysis in critically ill COVID-19 patients. Methods: Our retrospective observational study included 91 patients with critically ill SARS-CoV2 infection and renal failure admitted to the intensive care unit of our hospital from July 2020 to September 2021, who underwent acute intermittent peritoneal dialysis. Results: The demographic, laboratory, and treatment parameters were compared between survivors and non-survivors. Variables, like increased mean age (49.88 vs. 59.07 years), presence of diabetes mellitus (36.4% vs. 63.8%), increased lung involvement (57.3% vs. 75.0%), mechanical ventilation (15.2% vs. 70.7%), systolic (84.3 vs. 77.5 mm of Hg) and diastolic (59.09 vs. 42.93 mm of Hg) blood pressures, were associated with poor outcomes. The use of hypertonic PD (63.6% vs. 37.9%), better urea reduction ratios (44.33 vs. 39.84), and increased PD cycles (66.52 vs. 44.26) were associated with a better outcome. Complications, like haemorrhage and peritonitis, occurred in 10.9%. Conclusion: PD is a cost-effective bedside RRT that can be considered an effective option in critically ill COVID-19 patients. Good urea clearance, hemodynamic stability, and minimal resource requirements are also the features that favour peritoneal dialysis.

Acute Intermittent Peritoneal Dialysis in Critically Ill COVID-19 Patients with Renal Failure: Saviour or Succourer

Background: The COVID-19 pandemic has led to an increase in critically ill patients with renal failure, with many requiring renal replacement therapies. Unfortunately, many of them are too critically ill to tolerate intermittent hemodialysis. In the setting of limited resources, we did bedside acute intermittent peritoneal dialysis for critically ill COVID-19 patients with hemodynamic instability with or without ventilator support admitted to our intensive care unit. Objective: The aim of the study was to determine the outcome of intermittent peritoneal dialysis in critically ill COVID-19 patients. Methods: Our retrospective observational study included 91 patients with critically ill SARS-CoV2 infection and renal failure admitted to the intensive care unit of our hospital from July 2020 to September 2021, who underwent acute intermittent peritoneal dialysis. Results: The demographic, laboratory, and treatment parameters were compared between survivors and non-survivors. Variables, like increased mean age (49.88 vs. 59.07 years), presence of diabetes mellitus (36.4% vs. 63.8%), increased lung involvement (57.3% vs. 75.0%), mechanical ventilation (15.2% vs. 70.7%), systolic (84.3 vs. 77.5 mm of Hg) and diastolic (59.09 vs. 42.93 mm of Hg) blood pressures, were associated with poor outcomes. The use of hypertonic PD (63.6% vs. 37.9%), better urea reduction ratios (44.33 vs. 39.84), and increased PD cycles (66.52 vs. 44.26) were associated with a better outcome. Complications, like haemorrhage and peritonitis, occurred in 10.9%. Conclusion: PD is a cost-effective bedside RRT that can be considered an effective option in critically ill COVID-19 patients. Good urea clearance, hemodynamic stability, and minimal resource requirements are also the features that favour peritoneal dialysis.

Activation analysis and radwaste assessment of CFETR

The materials in the fusion system will be activated by the neutrons generated from D-T fusion reactions, causing the material with activity and decay heat at a variety level among the system. Predicting the amount of radwaste produced in the Chinese Fusion Engineering Testing Reactor (CFETR) and the time-evolution feature of the radwaste is of great importance to the minimization of waste and determine the management strategy. The purpose of this paper is to minimize the quality and quantity of the activated solid waste as low as reasonably achievable via source control, recycling and reuse, clearance, optimization of the management at the designing phase of CFETR. A detailed 3D model for CFETR is created to calculate the neutron spectra and fluxes of all non-void cells of the model. The inventory calculation for each cell with the given irradiation scenario and the cooling scheme was then carried out with FISPACT-II. The extensive calculation, data analysis, and post-processing are performed using a data processing code to calculate the component averaged activation responses and the waste classifications. The results suggest that the in-vessel materials exposed to high level neutron fluxes can hardly meet the clearance and low-level waste requirements, but they can be recycled with an advanced remote handling system shortly after shutdown or a conservative remote handling system after temporary storage within 100 years. The vacuum vessel, port plug, cryostat, and coils can be recycled with a conservative remote handling system with temporary storage. Especially, the port plug, cryostat, and central solenoid are clearable with temporary storage of 100 years. The influence of the operation time of in-vessel components on the radwaste severity and quantity is also evaluated. The severity of the radwaste increases when the operation time increases from 1000 to 3000 MWY, then decreasing with operation times longer than 3000 MWY. The detailed operation plan should be determined with comprehensive consideration of the important factors, including the influence on the radwaste severity. The allowed impurity level is also estimated, finding that the Uranium in the breeding zone and the SS316L used in divertor should be blamed for the intermediate-level waste production of blanket and divertor.

Youth sport parents’ familiarity and perceptions of concussion legislation

Objectives In an effort to reduce the negative health consequences often associated with concussions among young athletes, all U.S. states and the District of Columbia enacted youth concussion legislation between 2009 and 2014. This study explored youth sport parents’ (1) familiarity with their state's concussion legislation, and (2) perceptions about the need for additional legislative provisions not currently found in such laws. Methods Cross-sectional online survey data were obtained from parents ( n = 430) of youth sport athletes from 22 U.S states. Results Primary findings suggest that 67% of parents were moderately to extremely familiar with the removal from play requirement; 69.9% were moderately to extremely familiar with mandatory concussion training for coaches; and 75.1% were moderately to extremely familiar with the medical clearance requirement for athletes to return to play. In regard to perceptions, approximately half (50.2%) believed it is essential to mandate parent/guardian notification when a child suffers a potential concussion; and 42.8% believed it is essential to include a penalty/sanction for violating the statute. Based on the results of a multivariable logistic regression model, a significantly greater familiarity of concussion legislation was found among parents who were White/Caucasian, had advanced degrees, had higher household incomes, or were urban residents. Conclusions Our findings suggest that most youth sport parents have a sound understanding of concussion legislation and believe that the laws should be revised to improve best practices in preventing and managing concussions. Parents who face socio-cultural and economic barriers can benefit most from having access to credible information about their state's concussion law.

Anaesthetic considerations in posterior instrumentation of scoliosis due to spinal muscular atrophy: Case series of 56 operated patients.

Spinal muscular atrophy (SMA) is a rare illness that often leads to severe kyphoscoliosis. This case series adds to the heretofore sparse information as regards the anaesthetic management of SMA scoliosis patients. This retrospective study reviewed the charts of 79 SMA patients (type II n=34 and type III n=45) presenting for possible scoliosis surgery during the time period 2007-2019. Special attention focused on preoperative assessment and clearance requirements, anaesthesia protocol and postoperative handling. Out of 79 patients, 17 did not receive clearance for the procedure mostly due to grave respiratory insufficiency. Out of 62 patients with clearance for both surgery and anaesthesia, 56 patients [44 females, 12males; age mean±SD (range) 22±7.3 (10-40) years] underwent the procedure. Their forced vital capacity and forced expiratory volume in 1s were mean±SD (range) 1.41±0.53 (0.61-2.65) L and 1.26±0.47 (0.52-2.27) L, respectively. Intubation difficulties and their resolution, e.g. with the help of fibreoptic technique and video laryngoscopy, are described. All 56 patients were extubated in the operating room postoperativley. Patients stayed at the postanaesthesia care unit for one (n=48) or two (n=8) nights. A considerable amount of the patients (19/56) developed hypokalaemia postoperatively. This analysis is one of the bigger series of its kind and adds insight into the preoperative clearance process, the anaesthetic protocol and some of the postoperative complications, e.g. the tendency for developing postoperative hypokalaemia which has not been reported previously.

Study on Combined Energy Absorption Support for Rockburst Disaster Control in Tunnelling

In order to better realize the rockburst disaster control mechanism and approach, the rockburst response of concrete blocks with different energy absorption levels under different energy storage conditions was observed and analyzed by loading tests. The occurrence and control mechanism of rockburst were explored from the perspective of energy aggregation and energy dissipation. On this basis, a combined energy absorption support system of concrete-filled steel tube frames and hollow steel pipes for rockburst disaster control was designed, and the effectiveness of the system was verified by numerical simulation and field tests. The results of loading tests show that the failure mode of the specimens changes from static failure to dynamic burst under energy storage loading. The occurrence of rockburst is inevitable when the energy supply is sufficient, but the disaster can be reduced or eliminated by strengthening constraints and improving energy-absorbing capacity to transform rockburst into large deformation. The combined structure consists of the hollow steel pipes being energy-absorbing part and the concrete-filled steel tube frames being strong confinement part was proposed to control rockburst disaster in tunnel support. The numerical analysis on the dynamic response of the support under strong rockburst impact shows that the hollow steel pipes effectively reduced the impact force on the concrete-filled tube frames, and accordingly, the deformation of the entire support system decreased. Given the condition that the hollow steel pipes be able to absorb all the impact energy during deformation, the smaller the strength of the hollow steel pipe is, the smaller the impact force and the displacement is. The combined energy absorption support provides an effective solution for rockburst disaster management in tunnels with strict clearance requirements.

Safety Performance Enhancement Scheme for Munition Storages by applying the Concept of Shallow Underground Configurations

Practical demand for the expansion of military ammunition and explosives storage in both volume and number has been increased, but due to the regulations applying on safety distance that require those facilities to be isolated from a civilian presence there are constant complications that arise. Recent incidents include petitions to either alleviate said regulations or relocate several ammunition storage facilities neighboring civilian areas are further development. Two types of underground ammunition storage facilities wold be considered in practice; the first is the tunnel-type which is applicable to areas that have sufficient depth of the cover and the latter is the sub-surface type that retains a sufficient depth of soli layer which can especially be utilized in areas that do not meet clearance requirements nor have geographical limitations. For the sub-surface type storage, there are two construction schemes for construction to meet safety-distance requirements. The existing popular ECMs (Earth Covered Magazines) have shallow soil cover for just plantation camouflage that is not affect the pressure suppression effect due to the internal explosion. Therefore, the scheme of the increasing soil cover depth to some amount, if applicable, pressure and fragment suppression can be achieved. The open-cut method for new construction is easily applied for this purpose in the field. This study addresses the safety distance reduction effect by increasing the soil cover depth on the ECM type storage facility by applying theoretical and numerical analysis.

Systematic Approaches and Analyses on Voltage Uprating of 132 kV Transmission Lines: A Case Study in Malaysia

With the ageing infrastructure and fast-growing demand faced by utilities worldwide, voltage uprating is one of the most effective solutions and strategic approaches in asset management decisions. In this study, a systematic voltage uprating method is used to propose the new voltage level, based on the existing transmission lines’ physical structure, by utilising appropriate techniques. Prior to work conducted, the existing 132 kV transmission line was first examined in terms of the clearances and the components attached, and a technical issue on the clearance under still air was found to be a significant concern, particularly on phase-to-earth arrangements. Next, the proposed techniques and processes, by increasing the insulation strength and improving air conductor clearances, were used for the individual existing 132 kV transmission tower. The proposed voltage uprating of the 132 kV transmission tower comprehensively examines phase-to-earth under normal and extreme wind conditions based on electrical clearance requirements for 275 kV transmission lines. The proposed uprating model was then simulated using the Finite Element Method (FEM)-based commercial software under several lightning conditions, i.e., various basic lightning insulation levels (BIL) and different flashover mechanisms, taking into consideration still air and wind conditions for the voltage profile and its insulation strength analyses. The study found that the voltage profile condition for the proposed voltage uprating model was able to withstand its BIL under all conditions and thus satisfied the electrical requirement needed.

Issues and Challenges in Voltage Uprating for Sustainable Power Operation: A Case Study of a 132 kV Transmission Line System in Malaysia

Ageing grid infrastructure is a critical issue that is currently faced by electrical utilities worldwide, resulting in crucial decisions that must be made for the replacement, repair, or refurbishment of assets under constrained budgetary conditions, as well as other factors. As one of the fastest-developing countries globally, Malaysia is steadily growing in terms of its cumulative population, large industries, and advanced transportation sector, leading to an increasing electricity demand and, consequently, putting stress on electric utility providers to meet these tremendous demands. Significant concerns in the new development of transmission in Malaysia are the environmental issues, which involve exploration in gazetted areas and forest reserves. This paper describes the issues and challenges in developing a new transmission line system in Malaysia. In recent years, uprating existing transmission line systems has been one of the best asset management decisions for electric utility operators in order to meet such a demand for capacity. This paper assesses the technical issues and conventional methods of uprating the voltage of an existing transmission line system. The initial study found that the phase-to-Earth clearance does not fulfil the electrical clearance envelope. The study on the existing 132 kV transmission line system further analysed these issues and proposed an appropriate technique for uprating to a 275 kV transmission line system. Finally, the results indicate that the voltage uprating of the 132 kV transmission line system to 275 kV is able to satisfy the electrical clearance requirement envelope.