IEC Recommendations Research Articles

Proposed optimized energy plan for the largest island of South Korea based on full renewable energy resources

The current study's objective is to evaluate wind and solar energy and select the finest kind of energy systems having minimum levelized of energy systems by using Home Pro software for Jeju Island, the largest island in South Korea. Using Weibull and mean wind speed diagrams, the wind conditions in the initial section of this study are explained. To assess the wind potential of every area, size and form criteria are offered. It was found that two main wind directions were southeast or southwest, with southwest being more common. Finally, based on the wind conditions at each site and IEC recommendations, a set of five wind turbines that were best suited for each location were shortlisted. Each wind turbine's performance was assessed using technical criteria, that is, monthly energy production, annual energy production, and capacity factors. Similar to this, economic considerations such as the levelized cost of electricity, internal rate of return, payback period, and net present value were also made. A Hanjin model HJWT 87/2000 is best suitable for Jeju Island in the event of an off-shore wind farm, according to the findings. To explore the implications of modifying the hub height of the turbines on the economics of wind generating, a thorough economic sensitivity analysis is also included. The second section explains the solar potential of the Island. The average solar energy potential of Jeju Island is estimated to be 13.775 Mj·m2·day−1. To cover the energy demand and supply gap for Jaju Island, various types of local electricity generators and batteries have been studied for finding the optimal energy system for the island.

Electrical design for the conversion of existing UK HVAC overhead lines to HVDC operation under severe pollution conditions, ranging from 170 to 500 kV DC

This paper provides the HVDC electrical design of three existing UK HVAC overhead lines, two of which constitute 85% of the UK transmission overhead line system. The designs are based on CIGRE and IEC recommendations. Also, the verification of the electrical stress requirements on the insulators is performed by means of finite element simulations. The paper shows that the HVDC converted tower lines would carry 1.6 to 2.9 times the power of the original HVAC lines, depending on tower type, insulation arrangement, and environmental conditions.

The systematization of bending-sensitive fiber light guides

The results of systematic analysis of existing recommendations on fiber light guides. The systematization of physical parameters and operational characteristics of standardized fiber light guides has been carried out. Four informative parameters have been identified to assess the effect of fiber bends on the quality of fiber optic sensors. The purpose of the work is systematization of the ITU-T and IEC recommendations, as well as to assess the influence of bends on the fiber types in terms of the quality of communication lines and fiber-optic sensors of physical quantities.

Safety and Risk of Operating Facilities: Rapid Assessment Methodology

Two methods for methodology uses “risk indices” (dam condition index I), as well as “fuzzy logic methods” to combine the original quantitative and qualitative (expert) information on the operated dam condition. The approach applied is in accordance with the recommendations of IEC 31010: 2019. Risk Management — Risk Assessment Techniques. Deterministic assessments of the condition in the form of “risk indices” were also used as input data in assessing the probability of the failure and in developing a probabilistic risk assessment methodology. The original database, as well as the damage assessment scale, modified in the course of the research, summarize the experience of surveys and examination of safety declarations of more than 180 hydraulic works in Russia. A description is given of the methods of initial assessment and digitization (quantification) of the condition index I, as well as combining the initial quantitative and qualitative (expert) information about various damages. The practical feasibility and the possibility of categorizing (with fuzzy boundaries) conditions and levels of damage to hydraulic structures are shown. With regard to various conditions and levels of damage, proposals are made for practical actions to ensure the safety of dams in the process of monitoring, inspection, development of a reconstruction project and its expertise. As a result of the research, the dependence of the probability of the failure pfailure on the average value of the Iср index has been established and the graph “pfailure – Iср” is presented, which is well described by the exponential and is convenient for practical application. The value of I ср is determined according to the data of visual and instrumental control of the dam condition of the as well as according to expert estimates. The methodology for creation the indicated graph is presented. The creation of this graph became possible on the basis of: statistical processing, proof of the “normality” of the distribution of the I indices and the estimation (according to the distribution functions constructed for each level of damage) the probability of the failure pfailure, as well as during the survey and examination of the dam project. Proposals are formulated for the practical application of the proposed methods for assessing the risk of operating dams, and the near-term prospect of research in the field of risk assessment and ensuring dam safety is formulated.

Performance comparison of an extrapolation chamber in computed tomography standard beams of two laboratories

The doses received by the patients during the computed tomography (CT) exams are the highest when compared to other diagnostic radiology procedures. This fact makes it so important to keep the quality control using the correct instrument. For dosimetry in CT, a pencil type ionization chamber is usually utilized with a sensitive volume length of 10 cm. A comparison of the performance of an extrapolation chamber in two different laboratories, at the Instrument Calibration Laboratory (LCI) from Instituto de Pesquisas Energéticas e Nucleares (IPEN, Brazil) and at the National Physical Laboratory (NPL, UK) was undertaken. Two chamber characteristics were determined (zero depth and extrapolation curve), and the main recommended characterization tests were performed (stabilization time, saturation curve, polarity effect, ion collection efficiency, linearity of response, and variation of response with source-detector distance). This extrapolation chamber was calibrated using the standard system of NPL laboratory, and the energy dependence was determined. The results obtained were within the international recommendations of IEC 61674, except for the energy dependence, as already expected. This study also established a reference system for the LCI of the IPEN, using a homemade extrapolation chamber for X-ray CT beams. Using the extrapolation curves obtained in the characterization tests and the correction factors of ionic recombination, and scattering and fluorescence, the air kerma rates were obtained, as a reference system in standard laboratory computed tomography beams. The last correction factor was obtained using computer simulations by the MCNP5 code (Monte Carlo). Moreover, two pencil type ionization chambers were calibrated using the replacement method in relation to the extrapolation chamber.

Design and characterization of a lightweight underactuated RACA hand exoskeleton for neurorehabilitation

The spread of the use of robotic devices in neuro-rehabilitation therapies requires the availability of lightweight, easy-to-use, cost-effective and versatile systems. RobHand has been designed with these goals in mind. It is a hand exoskeleton especially suitable for patients suffering from spasticity in the fingers since it is easy to place in the hand and, from an underactuated design, allows both flexion and extension of the fingers. In this work, the structural characteristics, the mechanical design and the development and validation of the kinematic model of the device are presented, all of which has been carried out taking into account the recommendations of the new IEC 80601-2-78 standard, which formalizes the concept of RACA (Rehabilitation, Assessment, Compensation, Alleviation) robot and addresses aspects of efficiency and safety, essential in this type of equipment.

Led lamp driver modelling

Currently, there is an increase in the use and production of energy-saving lamps of various types – fluorescent and LED ones. However, it has been found that the use of technologies that have proven themselves in the creation of luminescent sources for LED light sources is ineffective. The use of traditional secondary optics for LED luminaires makes it difficult to create an effective heat sink from LEDs, while the durability of LEDs significantly depends on the heat sink. Another important issue when designing LED luminaires is choosing the right driver. The power consumption of LEDs from the primary network depends on the efficiency of the driver used. The choice of the type of driver also determines the amount of heat that should be removed from its elements. A significant factor influencing the choice of a driver is also the possibility of its operation in conjunction with a voltage regulator – a dimmer, in order to control the illumination. It is also necessary to take into account the IEC recommendations that require manufacturers to use active power factor correctors for devices with switching power supplies and / or electronic ballast with a power of 20 watts or more. Therefore, there is a task of developing a highly efficient driver for use in LED luminaires. In the process of reviewing modern drivers, a driver based on the LT3799 microcircuit from Linear Technology was selected for further research, which is distinguished by high efficiency, working with a large number of produced LEDs, has a built-in active power factor corrector, and allows the use of dimmers. The inclusion of the driver chip recommended by the manufacturer was applied, with the addition of noise suppressing components. The galvanic isolation of the power supply circuits of the LED matrix is provided. Next, the analysis of the characteristics of the selected circuit design solution is carried out using computer simulation. LTSpice EDA was chosen as a modeling tool, which is distinguished by its versatility, ease of use and high reliability of results in comparison with similar software products. The modes of operation are analyzed depending on the requirements for the pulsation of the emitting matrix, the operation of the power factor corrector, and the suppression of interference into the industrial network from the operation of the source is estimated. Various options for the development of the circuitry implementation of the driver based on the LT3799 microcircuit and the operating modes of the most heavily loaded elements are analyzed: an inductor, a key transistor, a damper circuit, a diode in the power supply circuit of an LED matrix. Optimal values of circuit components and parameters of winding elements were selected. It is shown that due to the operation of the power factor corrector, the shape of the current consumption from a sinusoidal voltage source is also almost sinusoidal, which leads to an almost active nature of the load. The modes of operation of the LED matrix for the nominal supply voltage and for the reduced one (with a dimmer) are considered. Methods of implementation of a soft start of an LED matrix are described. Based on the results of the work, conclusions are drawn that summarize the expediency of using the developed driver for an LED device based on the LT3799 microcircuit.

Research of the photobiological safety of led lamps and luminaires for general lighting

The paper analyzes the methods of assessing the photobiological safety of LED light sources according to international standards. It provides information on test equipment for determining the spectral composition of radiation and photometric parameters on the basis of which LED products are classified by risk groups of blue light. LED lamps and luminaires for general lighting in various spheres including household, public and office premises, outdoor lighting, etc. are studied. The level of danger of blue light is assessed at a distance at which the illuminance of 500 lux is formed, as well as at a distance of 200 mm (the most unfavorable conditions) according to the recommendations of international standards IEC 62471, IEC/TR 62471-2 and IEC/TR 62778. The results of the study of certain industrial samples of LED lamps and luminaires available on the Ukrainian market are presented.It is shown that the vast majority of LED products for general lighting have photometric parameters that do not exceed the group of insignificant risk RG1. All studied lamps in which low-power LEDs and bulbs with light scattering coating are used belong to the general group RG0 (no risk). Luminaires with low-power and medium-power LEDs, that have diffuse light diffusers, also correspond to the risk group RG0. Only luminaires with bright small-sized LEDs that don’t have the light diffusers (angular size less than 11 mrad) exceed the limits of the RG1 low-risk group. The number of such lamps does not exceed 10% of the studied products. At a distance at which an illumination of 500 lux is formed, the danger of blue light does not exceed the RG1 group. When the photobiological safety of blue light was measured from a distance of 200 mm, part of the luminaires with RG0 were moved to the group RG1, and luminaires from the group RG1 were moved to the group RG2. For luminaires belonging to the group RG2, the limit distances at which the luminaires still belong to the group RG1 were calculated.It was noted that a set of test equipment for determining the spectral composition of radiation and photometric parameters, as well as the software used to process the measurement results, significantly increases the productivity of assessing the photobiological safety of LED products. It was proposed that regulatory documents and catalogs for LED lamps and luminaires should declare the maximum luminance of these lamps.

Establishment of diagnostic X-ray air kerma standard in Taiwan

Diagnostic X-ray air kerma standards were established at the Institute of Nuclear Energy Research (INER, Taiwan) in accordance with the recommendations of IEC 61267. The radiation qualities established by INER include IEC 61267 RQR (RQR 3-10), RQA (RQA 3-10) and RQT. Among them, RQR is used to simulate the energy spectrum generated from the X-ray machine, RQA is used to simulate the energy spectrum after passing through the human body, and RQT is used to simulate the energy spectrum in computed tomography (CT).A tungsten target X-ray machine, 99.9% pure aluminum and copper filters were used to build the IEC 61267 radiation qualities. A cylindrical free-air chamber (FAC) is used as the X-ray air kerma primary standard. The FAC correction factors, including air attenuation, window attenuation, ion recombination, photon-scattering, electron-loss and shadow-effect, were evaluated by experiments or Monte Carlo methods.The half value layers (HVL) of these radiation qualities were measured by FAC, and the HVL differences between INER and IEC 61267 are less than 3%. The uncertainty of measurement was evaluated according to ISO GUM, and the relative standard uncertainty of primary standard is 0.53% (k = 1). An ionization chamber (Exradin A5) was sent to PTB and calibrated with IEC 61267 RQR and RQA qualities. When comparing the calibration factors between PTB and INER, the differences are less than 1.25%.The air kerma standard of diagnostic X-ray has been established at INER, and it will provide dose calibration services in Taiwan to improve medical quality.

Elaboration and Performance Analysis of a Bio-Based Insulating Liquid from Castor Oil for Power Transformers

The research for new mineral oil substitutes focuses on vegetable oils known for their biodegradability and low toxicity. This paper focuses on the development and analysis of physicochemical and dielectric properties of a bio-based insulating liquid from castor oil. Castor oil is an inedible tropical resource. It has a good annual oil yield and is widely available in developing countries. Cold pressing of castor seeds is the most appropriate non-chemical process for extracting oil. A refining process was used to remove metal and chemical residues. Refined Castor Oil was filtered and degassed in order to minimize the dissolved gases, solid particles and moisture. A transesterification operation was performed to significantly reduce viscosity oil. Finally, obtained Castor Oil Methyl Esters (COME) are finally distilled in a rotary evaporator under vacuum to remove traces of water and methanol. Physicochemical properties as visual examination, relative density, kinematic viscosity, and acidity were measured in accord-ance with ASTM D6871. AC Breakdown voltage was performed according to IEC 60156, and had been analyzed using Weibull distribution. Processed Castor Oil (PCO) has low viscosity than certified transformer vegetable oils (BIOTEMP, FR3) and high Dielectric Strength (74.67 kV/2.5 mm). Partial Discharges characteristics including the Partial Discharge Inception Voltage and the Partial Discharge Propagation Voltage were also investigated according to the recommendations of IEC 61294. PCO has satisfactory properties for their use as an insulating oil for transformer.

Establishment of radiation qualities for radiodiagnostics in LCR/UERJ according to IEC 61267 and TRS 457

The main goal of this work is to establish the radiation qualities of the Laboratório de Ciências Radiológicas (LCR) conventional X-ray equipment for calibrations in radiodiagnostics according to the recommendations of IEC 61267 and TRS 457. Tests were conducted to evaluate the homogeneity of the radiation field, high voltage applied to the X-ray tube, scattering, half-value layers (HVL) and homogeneity coefficients. The results obtained that characterize the radiation field, satisfy the conditions required by TRS 457. Invasive high voltage measures presented results compatible with the requirements of this standard. The HVL measures showed that for the first HVL the tolerance limits of IEC 61267, and the values for the homogeneity coefficients were within the limits established. The quality tests performed in this work were highly satisfactory in meeting the standard requirements. Thus, the main goal was achieved, and the methodology can be used by other similar X-ray systems.

Relationship between Acoustic Power and Acoustic Radiation Force on Absorbing and Reflecting Targets for Spherically Focusing Radiators

Total acoustic output power is an important parameter required by standards for most ultrasonic medical equipment including high-intensity focused ultrasound (HIFU) systems. Radiation force balances are routinely used; however, radiation force is not strictly dependent on the ultrasound power but, rather, on the wave momentum resolved in one direction. Consequently, measurements based on radiation force become progressively less accurate as the ultrasound wave deviates further from a true plane wave. HIFU transducers can be very strongly focused with F-numbers less than one: under these conditions, the uncertainty associated with use of the radiation force method becomes very significant. International Standards IEC 61161 and IEC 62555 suggest plane-wave correction factors for unfocused transducers radiating onto an ideal absorbing target and focusing corrections for focused transducers radiating onto ideal absorbing targets and onto conical reflecting targets (IEC 61161). Previous models have relied on calculations based on the Rayleigh integral, which is not strictly correct for curved sources. In the work described here, an approach combining finite element methods with a discretization of the Helmholtz equation was developed, making it possible to model the boundary condition at the structure/fluid interface more correctly. This has been used to calculate the relationship between radiation force and total power for both absorbing and conical reflecting targets for transducers ranging from planar to an F-number of 0.5 (hemispherical) and to compare with the recommendations of IEC 61161 and IEC 62555.

Extended C37.118.1 PMU Algorithms for Joint Tracking of Fundamental and Harmonic Phasors in Stressed Power Systems and Microgrids

This paper extends synchrophasor algorithms approximating C37.118.1 filtering requirements to provide phasor measurement units (PMUs) with the capability of accurately tracking single-phase harmonic phasors subject to varying nominal frequency and out-of band interharmonic interference. The fastest solution is built on a Kalman filter (KF) bank responding with notches at harmonic frequencies, while the most accurate solution relies on a five-cycle finite-impulse-response filter with more than 80-dB harmonic rejection. Highly distorted standardized test signals following WECC and Hydro-Québec experiences for stressed transmission systems and IEC recommendations for medium- and low-voltage system distortions are used to demonstrate the good performance of the two algorithms in tracking nonstationary fundamental and harmonics quantities. The two schemes are compared advantageously in terms of computation speed and performance with a four-cycle short-time fast Fourier transform algorithm. Finally, the effectiveness of harmonic phasors-enabled PMUs is demonstrated on a generation-rich microgrid subjected to a severe fault, followed by an offnominal frequency operation in islanded mode and subsequent grid re synchronization.

음질 평가법의 표준과 연구 동향 - 전송 처리음 분야

음질 평가는 좋은 소리를 만들기 위해 필수적인 요소이며, 음향의 특성과 대상 시스템에 따라 다양한 방법이 사용되고 있다. 본 논문에서는 음질 평가법의 전반적인 방법론 및 전송 처리된 음향 신호의 품질 평가법에 대해 ITU-T, ITU-R, IEC, 그리고 ANSI 등의 권고안에 기술된 국제 표준을 중심으로 요약하고 분석하였다. 분야별로는 음성 명료도, 음성 음질, 그리고 오디오 음질 평가법을 다루었으며, 현재 사용되는 권고안의 기술적인 내용과 최신 연구 동향 및 향후 발전 방향 등에 대해 기술하였다. Assessing the quality of audio signals is an important consideration in making high quality sounds and various methods have been developed. This paper provides a general framework of sound quality and a technical overview of the international standard methods which are described in ITU-T, ITU-R, IEC and ANSI Recommendations in the speech intelligibility, speech quality, and audio quality areas. In addition, some recent findings and future works are included.

Quality control methodology and implementation of X-radiation standards beams, mammography level, following the standard IEC 61267

This study presents the results of the establishment of a quality control program developed and applied for the X-ray system of the Calibration Laboratory of IPEN. The X-ray standard beams, mammography level, using molybdenum and aluminum as additional filtration were established after the application of this quality control and the spectrometry of these qualities was made. The reference ionization chamber has traceability to the PTB. The radiation qualities RQR-M, RQA-M, RQN-M and RQB-M, following the recommendations of the IEC 61267 and the IAEA TRS 457 were established.

Capacitive Current Interruption With Air-Break High Voltage Disconnectors

Capacitive current interruption with air-break disconnectors in a high-voltage network is an interactive event between the circuit and arc with a variety of interruptions and reignitions. In this contribution, first, a theoretical analysis related to this interaction is presented. The effect of capacitances at the source side (Cs ) and load side (Cl ) is investigated. Three distinct frequencies are identified as contributing to the voltage and current events in the circuit. Besides the power frequency quantities, a medium frequency transient arises related to the excursion of voltage across capacitances to the applied voltage, and a high-frequency transient arises due to charge redistribution between load- and source-side capacitance at reignition. Second, experimental results from an interruption measurement are studied in detail. Typical waveshapes of voltages across the capacitances, disconnector, and currents through the disconnector show that the transients during interrupted are in agreement with the theoretical analysis. Reignition voltage of the air gap and energy input to the arc on reignition are also studied. It is concluded that besides a higher interruption current and a higher power supply level, a lower Cs /Cl ratio leads to more severe interruption and longer arc duration. Finally, the actual status of IEC recommendations on testing, that has taken into account this arc-circuit interaction, is summarized.

Implementation and characterization of a 320‐slice volumetric CT scanner for simulation in radiation oncology

Effective target definition and broad employment of treatment response assessment with dynamic contrast-enhanced CT in radiation oncology requires increased speed and coverage for use within a single bolus injection. To this end, a novel volumetric CT scanner (Aquilion One, Toshiba, Tochigi Pref., Japan) has been installed at the Princess Margaret Hospital for implementation into routine CT simulation. This technology offers great advantages for anatomical and functional imaging in both scan speed and coverage. The aim of this work is to investigate the system's imaging performance and quality as well as CT quantification accuracy which is important for radiotherapy dose calculations. The 320-slice CT scanner uses a 160 mm wide-area (2D) solid-state detector design which provides the possibility to acquire a volumetric axial length of 160 mm without moving the CT couch. This is referred to as "volume" and can be scanned with a rotation speed of 0.35-3 s. The scanner can also be used as a 64-slice CT scanner and perform conventional (axial) and helical acquisitions with collimation ranges of 1-32 and 16-32 mm, respectively. Commissioning was performed according to AAPM Reports TG 66 and 39 for both helical and volumetric imaging. Defrise and other cone-beam image analysis tests were performed. Overall, the imaging spatial resolution and geometric efficiency (GE) were found to be very good (>10 lp/mm, <1 mm spatial integrity and GE160 mm=85%) and within the AAPM guidelines as well as IEC recommendations. Although there is evidence of some cone-beam artifacts when scanning the Defrise phantom, image quality was found to be good and sufficient for treatment planning (soft tissue noise <10 HU). Measurements of CT number stability and contrast-to-noise values across the volume indicate clinically acceptable scan accuracy even at the field edge. Initial experience with this exciting new technology confirms its accuracy for routine CT simulation within radiation oncology and allows for future investigations into specialized dynamic volumetric imaging applications.

Dual Band Dual Polarized Antenna with High Efficiency for Base Transceiver Stations

In this paper new array element for use in dual band dual polarized antenna will be introduced that has high efficiency (more than 95%) and has high isolation in both 900 MHz and 1800 MHz bands. Also radiation pattern of this antenna is according to IEC recommendation.

Practical considerations in the verification of personal sound exposure meters

This paper analyses the problems that appear when calibration or verification of personal sound exposure meters is done following the recommendations of IEC 61252. The tests recommended in the standard to verify the characteristics of such instruments are discussed and alternative procedures are proposed to solve the problems detected. The two main problems detected are related to the duration of the process, which has a direct effect on the verification cost, and the measurement uncertainty. The use of procedures based on measurement modes that are not dependent on integration times, such as when measuring sound pressure level, is recommended whenever possible.

An objective approach for selecting ice or wet–snow design loads on transmission lines

Ice and wet–snow design loads affect the investment costs and the potential maintenance costs for overhead lines more than any other single loading case in most countries exposed to snow and freezing temperatures during winter. The dependence of ice loads on investment costs for both steel towers and wood poles as well as the climatic variations of icing are shown. The paper summarizes the need for such data and refers to IEC recommendations for procedures and measurements of loads, especially as probabilistic methods for design require more comprehensive information on ice accretions on overhead lines, including variations due to conductor configurations. Icing information from icing models based on general meteorological data is summarized, including the potential for future application of atmospheric boundary–layer models as used by weather forecasting centres. A methodology for handling some topographic influences is introduced. The paper concludes with two case studies, one for glaze ice and one for wet–snow loadings.