Low-voltage Installations Research Articles

Efficient Analysis of Noise Induced in Low-Voltage Installations Placed Inside Buildings with Lightning Protection Systems

This paper describes an efficient approach to the broadband analysis of lightning protection systems (LPSs) using the method of moments (MoM) implemented in the frequency domain. The adaptive frequency sampling (AFS) algorithm, based on a rational interpolation of the relevant observable (e.g., voltage, current, electric or magnetic field) which describes the properties of the LPS, is employed to reduce the number of samples computed by the full-wave MoM. This improvement is achieved by the quick comparison of two interpolants with the use of the Stöer–Bulirsch algorithm, which provides the frequency location of the next MoM samples for computations. This algorithm allows for the efficient localization of resonant frequencies while reducing the number of samples computed over the entire frequency range. In the instances when the induced noise is determined in low-voltage installations protected by various types of LPSs, reductions in computational overhead equal to 47.9× and 72.1× in broadband LPS simulations are obtained. Hence, the proposed approach allows for a significant reduction in computational overhead in comparison to standard, uniformly sampled simulations.

CONFORMIDADE DE PAINÉIS ELÉTRICOS COM A NR-10 E NBR 5410

As modern industry integrates into the era of automation 4.0, characterized by information exchange and connectivity, there are still industries with outdated processes and equipment. The NBR 5410 and NR-10 standards play crucial roles, stipulating requirements and safety measures for low-voltage electrical installations and protecting the health and safety of workers. Electrical panels, fundamental in this context, regulate industrial processes automatically and without human intervention, ensuring not only efficiency and productivity, but also safety and effective maintenance of operations. In view of the above, the study aims to analyze how electrical panels can be configured and adjusted to comply with Brazilian standards NR-10 and NBR 5410. This study adopts bibliographic methodology, extensively reviewing academic literature, articles, technical standards and relevant related documents the installation of electrical panels. A careful selection of primary and secondary sources will be made to ensure a comprehensive understanding of current and emerging practices in the field. The process includes an analysis of extracted data to identify patterns, challenges and opportunities for innovation, providing a solid basis for discussion and conclusions in the study. In this way, the application of these standards contributes to a cycle of continuous improvement in the electrical industry. By establishing safe and efficient procedures, standards not only protect the individuals directly involved, but also benefit society as a whole by ensuring the integrity and security of critical infrastructures.

Determination of the Effect of Harmonics on the Performance of Single-Phase Low Voltage kWh Meters

Low-voltage installation systems with 450 VA and 900 VA power are one of the most commonly used electricity distribution systems in Indonesia. In the previous study, adjustments to the load of household needs were clearly made, and measurements were made at the load of 450-900 VA because some users received payment subsidies. Two types of kWh meters in accordance with standards in Indonesia are used by testing the readings of analog and digital kWh meters, which are loaded according to the load pattern. The load used is varied based on the load pattern that has been described in Table IV. Installation evaluation in the form of installing filters and improving the cross-sectional area value is carried out. After the installation of the passive filter, the power quality at 450 VA and 900 VA full load conditions improved, with the power factor in the electrical system of the 450 VA home installation increasing from 0.916 to 1. Keywords: harmonics, kWh meter, electrical energy, non-linear load, Home Installation

Low-Cost System with Transient Reduction for Automatic Power Factor Controller in Three-Phase Low-Voltage Installations

In power engineering, the importance of maintaining a high power factor in low-voltage electrical installations is known. In power substations for industry, the usual method of coupling is to use an automatic power factor controller which connects capacitors banks (with electromagnetic contactors). Sometimes, AC reactors are connected to the phases of the capacitors banks (to reduce transient phenomena and the deforming regime), depending on the desired value of the power factor. This paper presents an analysis (more focused on experimentation) of a low-cost system for automatic regulation of the power factor with a reduction in transients and an increase in the life of contactors (eliminating the electric arc during switching on), with capacitors banks for low-voltage three-phase installations that connect the capacitors banks by means of one three-phase solid-state relay (an expensive device for a quality device; one is used for all capacitors banks) and using several electromagnetic contactors. The automatic power factor adjustment system has a controller with a microprocessor with six outputs, controlled by the phase shift between the current (measured with a current transformer proportional to the current in a bar) and the phase voltage, which is part of a system of distribution bars (L1,2,3, N) from which electrical consumers (e.g., induction motors) are supplied. To reduce transients when connecting capacitors banks, a three-phase solid-state relay and two related electromagnetic contactors are used for each capacitors bank. The automatic power factor controller is connected to two low-capacity PLCs that control the logic of connecting the capacitors banks to reduce transients. By using the proposed regulation system, a cheaper control solution is obtained compared to the use of one solid-state relay for each capacitors banks, under the conditions in which the power factor adjustment is made as in the classic solution. If twelve capacitors banks are used, the proposed installation is 22.57% cheaper than the classical power factor regulation installation.

Analysis and assessment of the knowledge regarding to exploitation of electrical installations, risks and due to electric shock

INTRODUCTION This study presents the dangers due caused by electric shock and how they affect the human body. This is an important issue, because each of the recipients of this study is a user of electrical installations and the number of devices that may carry an unwanted threat is constantly increasing in every household. AIM OF STUDY The main purpose of the study is to analyze the knowledge of studied population about low-voltage electrical installations in the places of their residence, as well as the danger and consequences of electrical shock. MATERIALS AND METHODS In order to verify the level of awareness of household electrical installations users, a survey was conducted, in which participants were given the opportunity to answer questions forming three main research problems. CONCLUSION A significant part of the collected results leads to the conclusion that, on average, every second person surveyed has significant shortcomings in basic training in the safe use of electrical installations, as well as its operation and, most importantly, in providing first aid to victims. A relatively large number of respondents are not aware of the need to perform maintenance work, technical inspections and basic activities ensuring safety for them and other household members. Introduction of mandatory prevention and cyclical training, e. g. during periodic building inspections, could be one of the steps to reduce the still high rate of fatal accidents due to electric shock in Poland.

Protection verification and designing while establishing collective prosumer's low-voltage electrical installation. A case study

Protection verification and designing while establishing collective prosumer's low-voltage electrical installation. A case study

Efficiency evaluation of photovoltaic systems with batteries considering different voltage levels

The incorporation of batteries into photovoltaic (PV) self-consumption systems in buildings has a high potential to improve the degree of decarbonization and consumer benefits. However, very few studies have addressed the evaluation and comparison of the energy performance of PV systems with storage for self-consumption in buildings. Furthermore, studies have omitted the influence of energy storage at different voltage levels, which is an important parameter in the development of High Voltage (HV) lithium batteries.Thus, a load control system was designed and connected to the output of two self-consumption PV systems with batteries operating at different voltages, to compare the energy efficiency under the same energy demand conditions and with identical solar irradiation levels.The results show the importance of considering the voltage level parameter, as the average energy efficiency of High Voltage Installation (HVI) was higher than that of Low Voltage Installation (LVI) by 3 % to 10 % over the range of load powers analysed. Furthermore, it is shown that the most significant energy losses were influenced by the inverter's energy conversion process. Therefore, to achieve good system optimization, manufacturers should decrease the losses in this process and ensure high energy efficiency in the operating voltage and power ranges.

Analysis of Energy Losses in the Novel Distributed Power Supply System for Trams

The traction substation in conventional power supply systems for trams is a bottleneck of the system. It requires the connection with medium-voltage grid, demands high values of instant power and its centralized topology generates additional energy losses. Since the availability of low-power photovoltaic (PV) generation is increasing in the utility system, we propose to replace conventional substations with a distributed system of low-power devices cooperating with low-voltage grid and PV installations owned by individual households. The proposed in this article distributed power supply system for trams (DPSS-T) consists of multiple traction aggregators (TAs) equipped with energy storage devices (ESDs) which are distributed along the tram line. In order to evaluate the benefits of applying DPSS-T this proposed system was compared with the conventional topology regarding the energy losses in terms of annual operation. Moreover, the following aspects have been studied for the wide range EDS sizes and PV generation: PV energy injection into the power utility system, the utilization of installed ESD, and the contribution of PV generation in energy consumed by traction vehicles. At the same time, the energy management for this new topology has been proposed. The ESDs are charged with relatively low power, between tram runs and discharged with full power during the runs. The suggested energy management eliminates peaks in substation power demand. The obtained results show that despite the fact that the proposed DPSS-T is supplied from low-voltage grid the energy losses are reduced by 58%–69%.

Design and Energy Analysis of Photovoltaic-Battery Prototype Considering Different Voltage Levels

Photovoltaic self-consumption systems are effective at reducing energy consumption from fossil fuels and carbon emissions. Incorporating energy storage into these systems enables improved energy management and the optimization of their operation. However, to date, few studies have evaluated and compared the energy performance of PV systems with battery storage. In this context, with the current development of High Voltage batteries, research is needed on energy storage at different voltage levels incorporated into PV systems for self-consumption. In this way, the design and operation of an experimental prototype are described, consisting of two photovoltaic systems for self-consumption with energy storage using batteries operating at different voltages. One of them operates at low voltage (Low Voltage Installation, LVI) and the other at high voltage (High Voltage Installation, HVI). Through experimentation, it was demonstrated which installation is more efficient. During commissioning, the results showed the importance of considering the voltage level parameter in a renewable energy production system for self-consumption, since the energy yield of the HVI inverter-battery set was higher than in the case of the LVI on almost all of the days of the month studied. In addition, both systems showed a strong dependence on weather conditions, causing higher energy losses in their components during days with lower solar energy production. Therefore, the need for further analysis of energy efficiency to optimize the integration of these systems into the building sector was demonstrated.

Behavior of Residual Current Devices at Earth Fault Currents with DC Component.

Low-voltage electrical installations are increasingly saturated with power electronic converters. Due to very high popularity of photovoltaic (PV) installations and the spread of electric vehicles (EV) as well as their charging installations, DC-AC and AC-DC converters are often found in power systems. The transformerless coupling of AC and DC systems via power electronic converters means that an electrical installation containing both these systems should be recognized from the point of view of earth fault current waveform shapes. In such installations, various shapes of the earth fault current may occur-a DC component of a high value may especially flow. The DC component included in the earth fault current influences the tripping threshold of residual current devices (RCDs)-the devices which are mandatory in certain locations. This paper presents results of the AC-type, A-type, and F-type RCDs sensitivity testing under residual currents of various compositions of the DC component. This testing has shown that the DC component may both degrade and improve the sensitivity of RCDs. Moreover, unexpected positive behaviors of RCDs in some circumstances under DC residual current is discussed. Therefore, recognizing the real sensitivity and behavior of RCDs from the point of view of the DC component is important for effective protection against electric shock, in particular, in PV installations and EV charging systems. The research results provide a new insight into the real behavior of RCDs in modern power systems and, consequently, the safety of people.

The effect of nonlinear loads on the underground distribution cables: a case study

Nonlinear loads have become more prevalent in all applications, including computers, transformers, and adjustable speed drives. The harmonic level of the underground distribution cables rises as a result of these loads. As a result, the cable layers' temperatures are affected by the harmonic levels. The purpose of this paper is to calculate the temperature distribution of a cable conductor and the soil around it under cyclic loading conditions, including the impact of linear and nonlinear loads. The IEC 60,853-2 standard is used to consider the thermal model of an underground cable. The finite element method is investigated to obtain a heat map of the cable layers and their surrounding soil. In this study, the small-scale model was constructed in the laboratory. The cable is installed using two methods at the same loading conditions. The heat transfer in the four-core low-voltage cable installation is measured. Furthermore, total harmonic distortion is measured using a Fluke 125 scope meter. The experimental results from the laboratory model proved that there was an extreme increase in the temperature of cable layers when the cable was installed inside the polyvinyl chloride duct in the soil compared with its installation directly buried in the soil. The results of the experimental tests are compared with simulation results.

Electrical safety in low-voltage DC microgrids with B-type residual current devices

Residual current devices (RCDs) are most popular devices used in low-voltage installations for protection against electric shock and fire. In cases of high risk of electric shock the application of RCDs is mandatory. Currently, the spread of local direct current (DC) microgrids is widely considered. This creates new challenges for protective systems, in particular those based on RCDs. The main purpose of the research is to test the operation of B-type RCDs by simulating the conditions that may occur in DC microgrids as well as assessment of the effectiveness of electrical safety with the use of such RCDs. The research has revealed that theoretically identical RCDs in terms of technical data can have different tripping properties, including no reaction to residual direct current, which poses a risk of electric shock. This signalizes the necessity of extension of the normative tests performed by manufacturers. The scope of these additional RCDs tests is indicated, from the point of view of the persons’ safety in DC microgrids.

Poboljšanje standardizovane procedure za verifikaciju kvaliteta niskonaponskih električnih instalacija

Periodic verification of the quality of low-voltage electrical installations is very important from the point of view of safety of people in the building from electric shock and initial fire caused by failures of low-voltage electrical installations (usually poor electrical contact). The standardized procedure for verifying the quality of electrical installations by electrical measurements involves checking which can determine with certainty only whether the protection system by automatic shutdown of the power supply in case of failure is effective or not. However, this check can only detect some poor electrical contacts in the circuit that are potential causes of fire. The paper provides an overview of research results conducted within the project of the Ministry of Education, Science and Technological Development of the Republic of Serbia (project record number 36018), on the basis of which the correction of the existing procedure of periodical verification of the quality of electrical installations is proposed. The proposed correction, which was developed based on the experience gained by performing periodical verification of the quality of electrical installations in the field, as well as analysis of measurement results obtained experimentally in laboratory conditions, allows poor electrical contacts to be detected in a timely manner.

Improved measurement accuracy of industrial-commercial thermal imagers when inspecting low-voltage electrical installations

The main contribution of this research is a general method for improving the measurement accuracy of industrial-commercial thermal imagers when inspecting various types of electrical equipment. The measurement of the peak temperatures of fuses and miniature circuit breakers, particularly those located in inaccessible or dangerous places, was used for the verification of the developed method. The method takes into account the influence of the inspected equipment surface emissivity, reflected background temperature, the equipment distance from the thermal imager and the angle of view on the accuracy of the measured peak temperature. A practice oriented algorithm, representing the basis for the corresponding Excel sheet, was also developed, making fault diagnosis semiautomatic. It was shown that the method/algorithm is applicable for a wide range of the tested equipment rated currents and for different industrial-commercial thermal imagers.

Review of Technical Design and Safety Requirements for Vehicle Chargers and Their Infrastructure According to National Swedish and Harmonized European Standards

Battery electric vehicles demand a wide variety of charging networks, such as charging stations and wallboxes, to be set up in the future. The high charging power (typically in the range of a couple of kW up to a couple of hundred kW) and the possibly long duration of the charging process (up to more than 24 h) put some special requirements on the electrical infrastructure of charging stations, sockets, and plugs. This paper gives an overview of the technical design requirements and considerations for vehicle charging stations, sockets, and plugs, including their infrastructure, according to the Swedish Standard 4364000, “Low-voltage electrical installations—Rules for design and erection of electrical installations”, and the corresponding harmonized European standards. In detail, the four internationally categorized charging modes are explained and the preferable charging plugs, including their two-bus communication, according to European Directives are shown. The dimensioning of the supply lines and the proper selection of the overcurrent protection device, the insulation monitor, and the residual current device are described. Furthermore, a comprehensive overview of the required safety measures, such as the application of an isolation transformer or the implementation of an overvoltage protection mechanism, and the limits for conducted electromagnetic emissions, such as low-frequency harmonics or high-frequency (150 kHz to 108 MHz) emissions, are given.

Using Energy Storage Inverters of Prosumer Installations for Voltage Control in Low-Voltage Distribution Networks

The paper includes the analysis of the operation of low-voltage prosumer installation consisting of receivers and electricity sources and equipped with a 3-phase energy storage system. The aim of the storage application is the management of active power within the installation to decrease the total power exchanged with the supplying network and thus reduce energy costs borne by the prosumer. A solution for the effective implementation of the storage system is presented. Apart from the active power management performed according to the prosumer’s needs, the storage inverter provides the ancillary service of voltage regulation in the network according to the requirements of the network operator. A control strategy involving algorithms for voltage regulation without prejudice to the prosumer’s interest is described in the paper. Reactive power is used first as a control signal and if the required voltage effect cannot be reached, then the active power in the controlled phase is additionally changed and the Energy Storage System (ESS) loading is redistributed in phases in such a way that the total active power set by the prosumer program remains unchanged. The efficiency of the control strategy was tested by means of a simulation model in the PSCAD/EMTDC program. The results of the simulations are presented.

ASPECTE CALITATIVE ȘI CANTITATIVE ALE FENOMENUL DE FEROREZONANȚĂ ÎN INSTALAȚIILE ELECTRICE DE JOASĂ TENSIUNE

The phenomenon of ferroresonance is generated by the interaction between nonlinear magnetic devices and capacitive elements in an electrical installation in which losses are reduced and which are constantly supplied by at least one energy source. Feroresonance is manifested by the appearance of overvoltages and overcurrents in the installation with strongly distorted waveforms. Also, the phenomenon is accompanied by other disturbances of the quality of electricity (voltage fluctuations, asymmetries, noise, etc.), which propagate in the network affecting the proper functioning of the entire installation. In addition, unlike linear resonance, ferroresonance allows the manifestation of several stable states (modes) for the same parameters of the network, these being imposed by the initial conditions in the installation and the moment of occurrence of the phenomenon. Thus, the vulnerability to low resonance of a low voltage installation has become an indicator of electricity quality. This paper presents a procedure for calculating and investigating this phenomenon based on the analysis of numerical solutions of systems of differential equations (nonlinear and non-autonomous), which models the transient phenomena that initiate the appearance of ferroresonance (usually switching processes). Also, modern means of investigation are used (3D visualizations in the phase plan or Poincaré diagrams), imposed by the difficulty of the quantitative analysis both in dynamic regime and in stationary regime of ferroresonance. In addition, methods and procedures are proposed to mitigate the effects of the ferroresonance phenomenon on equipment or network elements in electrical distribution installations.

Implementasi Metode Hazard Identification Risk Assessment And Risk Control Guna Peningkatan Keselamatan dan Kesehatan Karyawan di PT ABC

Zero accident was considered as the primary occupational health and safety value in manufacturing and service enterprises. PT. ABC provided electrical and instrument services, including a low-voltage installation, high-voltage installation and an instrument installation. This company is known to excellent electricity and instrument service providers across the country . Moreover, men’s power is used as a primary source to maintain these kind of services. Installation projects depend not only on the high working speed, but also on high working accuracy within certain timeframes . As a result, work accidents have occurred with a classification varying from minor to fatal accidents. The purpose of this research is to identify potential hazards to assess risk levels and obtain recommendations for preventing accident. The HIRARC method is employed as a research approach. This research is initiated through Hazard Identification, Risk Assessment and Risk Control. This research identified that two hazards were classified as extreme risk, three hazards as high- risk, eight hazards as moderate risk , and two hazards have been identified as low risk . Furthermore, a number of action lists have been suggested in order to minimize accident rates and finally the working conditions are designed to maintain zero accidents.

The Short-Circuit Protections in Hybrid Systems with Low-Power Synchronous Generators

Single-phase short-circuits are most often faults in electrical systems. The analysis of this damage type is taken for backup power supply systems, from small power synchronous generators. For these hybrid installations, there is a need for standard protection devices, such as fuses or miniature circuit breaker (MCB) analysis. Experimental research mentioned that a typical protective apparatus in low-voltage installations, working correctly during supplying from the grid, does not guarantee fast off-switching, while short-circuits occur during supplication from the backup generator set. The analysis of single-phase short-circuits is executed both for current waveform character (including sub-transient and transient states) and the carried energy, to show the problems with the fuses and MCB usage, to protect circuits in installations fed in a hybrid way (from the grid and synchronous generator set).

Prediction of power cables failures using a software application

This paper analyses the electrical performance of power supply cables in operation by investigating previous faults and forecasting faults using the Easyfit Professional 5.6 software program. The calculation of the maximum operating time until the first fault occurs is based on an algorithm for estimating the parameters entered in the application, respectively the intervals of good operation time between two successive faults. The case study presented in the paper analyses the probability of failure of a medium voltage power line, under the administration of a distribution operator, based on information collected during maintenance work on medium and low voltage installations in the analysed area.