Statistics regarding electrical accidents worldwide indicate that thousands of people are injured or killed every year. Electrical professionals working on the installation, maintenance, repair, and construction of electrical facilities are in fact the very people most likely to experience an electrical accident. Of these, electricians are the most vulnerable. Contact with electrical wiring or other electrical equipment is the most common cause of an electrical accident.
Achieving a zero number of electrical accidents will require a safe electrical installation, properly maintained over its lifetime, and an emphasis on the good condition of the measures protecting against electric shock and burns. This, together with a proper training of employees, will go a long way towards achieving this goal.
Interharmonics are voltages or currents with a frequency that is a non-integral multiple of the fundamental supply frequency, while each harmonic frequency is an integral multiple of the supply frequency. Interharmonics, always present in the power system, have recently become of more importance since the widespread use of power electronic systems results in an increase of their magnitude.
Interharmonics are caused by the asynchronous switching of semiconductor devices in static converters such as cycloconverters and pulse width modulation (PWM) converters, or by rapid changes of current in loads operating in a transient state.
This application note discusses the background, origin and measurement of interharmonics.
This application note discusses the use of active filters to reduce harmonic currents in installations. Active filters work by providing the harmonic current required by the load instead of it being drawn from the supply.
The major advantage of active filters is that they can be distributed around an electrical network in a decentralized manner, which enhances the effect of filtering. They can be programmed to respond to selected or all harmonic frequencies and quickly adapt to changes in load profile.
Interharmonics are voltages or currents with a frequency that is a non-integral multiple of the fundamental supply frequency, while each harmonic frequency is an integral multiple of the supply frequency. Interharmonics, always present in the power system, have recently become of more importance since the widespread use of power electronic systems results in an increase of their magnitude.
Interharmonics are caused by the asynchronous switching of semiconductor devices in static converters such as cycloconverters and pulse width modulation (PWM) converters, or by rapid changes of current in loads operating in a transient state.
This application note discusses the background, origin and measurement of interharmonics.
This application note discusses the use of active filters to reduce harmonic currents in installations. Active filters work by providing the harmonic current required by the load instead of it being drawn from the supply.
The major advantage of active filters is that they can be distributed around an electrical network in a decentralized manner, which enhances the effect of filtering. They can be programmed to respond to selected or all harmonic frequencies and quickly adapt to changes in load profile.
Nuisance tripping of circuit breakers is a common problem in many commercial and industrial installations. This application note explains the need to use true RMS measurement instruments when troubleshooting and analyzing the performance of a power system.
Nuisance tripping of circuit breakers is often caused by the load current being distorted by the presence of harmonic currents drawn by non-linear loads. Harmonic currents distort the current waveform and increase the load current required to deliver energy to the load. Many measurement instruments, even quite modern ones, use an averaging measurement technique that does not measure harmonic currents correctly. The readings may be as much as 40% too low. Circuit breakers and cable sizes may be underrated as a result.
True RMS meters, which take the complete distorted waveform into account, should be used instead.
Power quality (PQ) is a major concern for a large number of industrial sites and buildings. This guide provides an easy-reference to the major power quality phenomena, the problems they are causing, and measures to avoid those problems. It is unlikely that a single solution will be effective. Careful design of a solutions mix, tailored to the PQ problems experienced, and based on a detailed understanding of the causes of the PQ problems, is needed.
Transformers can be more than just static devices that transfer electrical energy. Separation transformers, isolation and extra isolation transformer play a major role in the protection of people and equipment. They come in all ranges, from very small (a few VA) to quite large (a few MVA), and although more expensive than autotransformers or transformers with simple separate windings, they are an easy way to solve problems that could arise concerning:
Protecting individuals from electrical shock
Avoiding critical equipment from losing power in the case of a first insulation fault
Protecting sensitive equipment from electrical noise
Creating a star point for equipment that require it
Arc flash incidents can be costly in terms of personnel injury and equipment repair/replacement. This presentation provides an overview of the NFPA 70E 2012 Standard for Electrical Safety in the Workplace and the requirements of the standards, which are intended to better protect electrical workers from injury when they work on energized electrical equipment. This includes all aspects of facility and employer responsibilities for compliance to the NFPA 70E standards, as well as the current status of OSHA enforcement of these standards. Copyright AIST Reprinted with Permission.
Voltage characteristics of grid electricity (EN 50160)Leonardo ENERGY
Three parties exert an influence on the power quality in the electric network: the network operator, the network user and the manufacturer of the network equipment. Standard EN 50160 represents a compromise between those three parties.
The important advantages of the EN 50160 standard are:
The definition of the voltage parameters important for power quality
The quantitative determination of reference values that can be used in the power quality evaluation
EN 50160 deals with the voltage characteristics in statistical or probabilistic terms. It gives recommendations that, for a percentage of measurements (e.g. 95%) over a given time, the value must be within the specified limits. This boundary value will be accepted as the compatibility level between the level of disturbances in the network and the level of immunity of equipment.
If the customer has higher requirements than the minimum performance criteria prescribed in this standard, they should instigate their own mitigation measures. Another option is to negotiate a separate agreement for a higher supply quality with the power supplier.
In this way, the responsibilities of the network operator, equipment manufacturer and user are matched and clarified.
Mitigating Arc Flash Hazards - A Simple Graphic Helps Visualize Five Distinct...Schneider Electric
The understanding and awareness of arc flash and related hazards has increased greatly in industry. However, the application of product or design solutions intended to reduce the hazard levels or mitigate the risk of arc flash events has received relatively little attention. A simple graphic will provide information on five distinct methods that have been successfully applied in arc flash mitigation solutions.
In electrical engineering terminology, transformers are regarded as electrical machines, although they only convert one form of electricity into another form of electricity. Due to this relatively simple function, among other reasons, their losses are lower than those of any equipment converting electricity into some other form of energy. They are probably the most efficient machines ever devised by man.
Transformer efficiencies are around 80% for very small units used in domestic appliances and nearly 99% at the level of distribution networks. The efficiency further increases with increasing unit power rating. The largest units achieve efficiencies of up to 99.75% at rated load and even 99.8% at half load. At first glance, it looks rather unlikely that there is any savings potential left that would be commercially significant, but in fact there is.
It is true that the payback periods are fairly long, but a transformer has a lifetime expectancy of well over 40 years and the majority of all transformers are operated continuously at a high degree of loading. As a result, an improved transformer design, primarily through the use of more active material, will usually pay off several times over the lifespan of the transformer.
Neutral sizing in harmonic-rich installationsLeonardo ENERGY
Both national and international standards for the conductor sizing of cables do not adequately take into account the additional heat load arising from harmonic currents. Some standards prescribe the maximum current values for four-conductor and five-conductor cables under the assumption that only two or three conductors are loaded. However, today’s harmonic situations may give rise to the fourth conductor (neutral) being fully loaded or even overloaded simultaneously with a balanced load on the three phase conductors. Other standards provide a general instruction that under a particular harmonic impact on the phase conductors, a certain additional load has to be taken into account for sizing the neutral conductor. However, the practitioner will usually not know how much harmonic impact arises from a particular load or group of loads.
In the following application note, an approach will be given to estimate the additional thermal impact due to harmonic currents in the LV power supply system of a building. Based on this estimation, it provides a methodology on how to dimension and select three-phase cables that are supposed to feed single-phase final circuits containing distorting loads.
Given that the core business of a hospital is the welfare of its patients, it is easy to understand why the intricacies of electricity are not a high priority. However, ensuring patient welfare requires a huge variety of medical appliances, which in turn, require electricity. Electricity is therefore a vital utility and any malfunction or interruption can quickly lead to disastrous consequences.
This combination—being absolutely vital but far from the primary concern of the organization—entails a certain risk.
Standards and regulations prescribe how a hospital’s electrical installations should be conceived and installed to ensure safety and reliability. Those regulations are complemented by the prescriptions of the equipment manufacturers. All these rules, however, create a complex tangle of information for the user, often making it difficult to figure out which rule has to be applied where and exactly how it has to be implemented. In this tutorial, we will try to shed light on those regulations and give a comprehensive overview.
Once safety and reliability are taken care of, the focus can shift to energy efficiency. The fact that efficiency is only of secondary priority for a hospitals’ electrical installation does not mean its impact cannot be significant. By focusing on energy efficiency, hospitals can often make surprisingly large savings on the total cost of ownership (TCO) of their installations and thus on the cost of the medical aid they render. This paper addresses a few of the major energy efficiency topics relevant to medical building management.
I would like to share some knowledge of surge protection devices.
This presentation highlights some concepts of surge and surge protectors.
Presentation Index is as follows:
> Types of Surge
> Sources of Surge
> Surge Current & Voltage waveform
> Importance of Surge Protectors
> Types of Surge protectors
> Location of Surge Protectors
Webinar - Electrical Arc Flash Hazards - Is your company in compliance?Leonardo ENERGY
This course is designed to equip the electrical consultant, system designer or any other professional responsible for designing or modernizing commercial and industrial electrical power distribution systems with the fundamentals of the Arc Flash Energy phenomenon.
Cable Conductor Sizing for Minimum Life Cycle CostLeonardo ENERGY
Energy prices are high and expected to rise. All CO2 emissions are being scrutinized by regulators as well as by public opinion. As a result, energy management has become a key factor in almost every business. To get the most out of each kilowatt-hour, appliances must be carefully evaluated for their energy efficiency.
It is an often overlooked fact that electrical energy gets lost in both end-use and in the supply system (cables, busbars, transformers, etc.). Every cable has resistance, so part of the electrical energy that it carries is dissipated as heat and is lost.
Such energy losses can be reduced by increasing the cross section of the copper conductor in a cable or busbar. Obviously, the conductor size cannot be increased endlessly. The objective should be the economic and/or environmental optimum. What is the optimal cross section necessary to maximize the Return on Investment (ROI) and minimize the Net Present Value (NPV) and/or the Life Cycle Cost (LCC)?
This paper will demonstrate that the maximizing of the ROI results in a cross section that is far larger than which technical standards prescribe. Those standards are based entirely on safety and certain power quality aspects. This means there is room for improvement—a great deal of improvement in fact.
Industrial Surge Protection: Why Use Mersen Surge Protection Devices?AutomationDirect.com
In this Slideshare you may gain a better understanding of what a power surge is, what may cause a power surge, and why using Mersen surge protection devices to protect your equipment is an easy and cost-effective solution that will save you money and downtime.
Voltage dips in continuous processes: case studyLeonardo ENERGY
This application note describes an industrial case study in a nylon extrusion plant. Investigation revealed a history disruptive dips at the plant with significant loss of production. Examination of the records showed that the plant was affected by faults in a wide area of the network; the objective of the study was to decide how to limit the exposure of the plant to these faults. The options for improvement include measures at the equipment, installation and network level. Several solutions are proposed and the cost of each estimated.
Nuisance tripping of circuit breakers is a common problem in many commercial and industrial installations. This application note explains the need to use true RMS measurement instruments when troubleshooting and analyzing the performance of a power system.
Nuisance tripping of circuit breakers is often caused by the load current being distorted by the presence of harmonic currents drawn by non-linear loads. Harmonic currents distort the current waveform and increase the load current required to deliver energy to the load. Many measurement instruments, even quite modern ones, use an averaging measurement technique that does not measure harmonic currents correctly. The readings may be as much as 40% too low. Circuit breakers and cable sizes may be underrated as a result.
True RMS meters, which take the complete distorted waveform into account, should be used instead.
Power quality (PQ) is a major concern for a large number of industrial sites and buildings. This guide provides an easy-reference to the major power quality phenomena, the problems they are causing, and measures to avoid those problems. It is unlikely that a single solution will be effective. Careful design of a solutions mix, tailored to the PQ problems experienced, and based on a detailed understanding of the causes of the PQ problems, is needed.
Transformers can be more than just static devices that transfer electrical energy. Separation transformers, isolation and extra isolation transformer play a major role in the protection of people and equipment. They come in all ranges, from very small (a few VA) to quite large (a few MVA), and although more expensive than autotransformers or transformers with simple separate windings, they are an easy way to solve problems that could arise concerning:
Protecting individuals from electrical shock
Avoiding critical equipment from losing power in the case of a first insulation fault
Protecting sensitive equipment from electrical noise
Creating a star point for equipment that require it
Arc flash incidents can be costly in terms of personnel injury and equipment repair/replacement. This presentation provides an overview of the NFPA 70E 2012 Standard for Electrical Safety in the Workplace and the requirements of the standards, which are intended to better protect electrical workers from injury when they work on energized electrical equipment. This includes all aspects of facility and employer responsibilities for compliance to the NFPA 70E standards, as well as the current status of OSHA enforcement of these standards. Copyright AIST Reprinted with Permission.
Voltage characteristics of grid electricity (EN 50160)Leonardo ENERGY
Three parties exert an influence on the power quality in the electric network: the network operator, the network user and the manufacturer of the network equipment. Standard EN 50160 represents a compromise between those three parties.
The important advantages of the EN 50160 standard are:
The definition of the voltage parameters important for power quality
The quantitative determination of reference values that can be used in the power quality evaluation
EN 50160 deals with the voltage characteristics in statistical or probabilistic terms. It gives recommendations that, for a percentage of measurements (e.g. 95%) over a given time, the value must be within the specified limits. This boundary value will be accepted as the compatibility level between the level of disturbances in the network and the level of immunity of equipment.
If the customer has higher requirements than the minimum performance criteria prescribed in this standard, they should instigate their own mitigation measures. Another option is to negotiate a separate agreement for a higher supply quality with the power supplier.
In this way, the responsibilities of the network operator, equipment manufacturer and user are matched and clarified.
Mitigating Arc Flash Hazards - A Simple Graphic Helps Visualize Five Distinct...Schneider Electric
The understanding and awareness of arc flash and related hazards has increased greatly in industry. However, the application of product or design solutions intended to reduce the hazard levels or mitigate the risk of arc flash events has received relatively little attention. A simple graphic will provide information on five distinct methods that have been successfully applied in arc flash mitigation solutions.
In electrical engineering terminology, transformers are regarded as electrical machines, although they only convert one form of electricity into another form of electricity. Due to this relatively simple function, among other reasons, their losses are lower than those of any equipment converting electricity into some other form of energy. They are probably the most efficient machines ever devised by man.
Transformer efficiencies are around 80% for very small units used in domestic appliances and nearly 99% at the level of distribution networks. The efficiency further increases with increasing unit power rating. The largest units achieve efficiencies of up to 99.75% at rated load and even 99.8% at half load. At first glance, it looks rather unlikely that there is any savings potential left that would be commercially significant, but in fact there is.
It is true that the payback periods are fairly long, but a transformer has a lifetime expectancy of well over 40 years and the majority of all transformers are operated continuously at a high degree of loading. As a result, an improved transformer design, primarily through the use of more active material, will usually pay off several times over the lifespan of the transformer.
Neutral sizing in harmonic-rich installationsLeonardo ENERGY
Both national and international standards for the conductor sizing of cables do not adequately take into account the additional heat load arising from harmonic currents. Some standards prescribe the maximum current values for four-conductor and five-conductor cables under the assumption that only two or three conductors are loaded. However, today’s harmonic situations may give rise to the fourth conductor (neutral) being fully loaded or even overloaded simultaneously with a balanced load on the three phase conductors. Other standards provide a general instruction that under a particular harmonic impact on the phase conductors, a certain additional load has to be taken into account for sizing the neutral conductor. However, the practitioner will usually not know how much harmonic impact arises from a particular load or group of loads.
In the following application note, an approach will be given to estimate the additional thermal impact due to harmonic currents in the LV power supply system of a building. Based on this estimation, it provides a methodology on how to dimension and select three-phase cables that are supposed to feed single-phase final circuits containing distorting loads.
Given that the core business of a hospital is the welfare of its patients, it is easy to understand why the intricacies of electricity are not a high priority. However, ensuring patient welfare requires a huge variety of medical appliances, which in turn, require electricity. Electricity is therefore a vital utility and any malfunction or interruption can quickly lead to disastrous consequences.
This combination—being absolutely vital but far from the primary concern of the organization—entails a certain risk.
Standards and regulations prescribe how a hospital’s electrical installations should be conceived and installed to ensure safety and reliability. Those regulations are complemented by the prescriptions of the equipment manufacturers. All these rules, however, create a complex tangle of information for the user, often making it difficult to figure out which rule has to be applied where and exactly how it has to be implemented. In this tutorial, we will try to shed light on those regulations and give a comprehensive overview.
Once safety and reliability are taken care of, the focus can shift to energy efficiency. The fact that efficiency is only of secondary priority for a hospitals’ electrical installation does not mean its impact cannot be significant. By focusing on energy efficiency, hospitals can often make surprisingly large savings on the total cost of ownership (TCO) of their installations and thus on the cost of the medical aid they render. This paper addresses a few of the major energy efficiency topics relevant to medical building management.
I would like to share some knowledge of surge protection devices.
This presentation highlights some concepts of surge and surge protectors.
Presentation Index is as follows:
> Types of Surge
> Sources of Surge
> Surge Current & Voltage waveform
> Importance of Surge Protectors
> Types of Surge protectors
> Location of Surge Protectors
Webinar - Electrical Arc Flash Hazards - Is your company in compliance?Leonardo ENERGY
This course is designed to equip the electrical consultant, system designer or any other professional responsible for designing or modernizing commercial and industrial electrical power distribution systems with the fundamentals of the Arc Flash Energy phenomenon.
Cable Conductor Sizing for Minimum Life Cycle CostLeonardo ENERGY
Energy prices are high and expected to rise. All CO2 emissions are being scrutinized by regulators as well as by public opinion. As a result, energy management has become a key factor in almost every business. To get the most out of each kilowatt-hour, appliances must be carefully evaluated for their energy efficiency.
It is an often overlooked fact that electrical energy gets lost in both end-use and in the supply system (cables, busbars, transformers, etc.). Every cable has resistance, so part of the electrical energy that it carries is dissipated as heat and is lost.
Such energy losses can be reduced by increasing the cross section of the copper conductor in a cable or busbar. Obviously, the conductor size cannot be increased endlessly. The objective should be the economic and/or environmental optimum. What is the optimal cross section necessary to maximize the Return on Investment (ROI) and minimize the Net Present Value (NPV) and/or the Life Cycle Cost (LCC)?
This paper will demonstrate that the maximizing of the ROI results in a cross section that is far larger than which technical standards prescribe. Those standards are based entirely on safety and certain power quality aspects. This means there is room for improvement—a great deal of improvement in fact.
Industrial Surge Protection: Why Use Mersen Surge Protection Devices?AutomationDirect.com
In this Slideshare you may gain a better understanding of what a power surge is, what may cause a power surge, and why using Mersen surge protection devices to protect your equipment is an easy and cost-effective solution that will save you money and downtime.
Voltage dips in continuous processes: case studyLeonardo ENERGY
This application note describes an industrial case study in a nylon extrusion plant. Investigation revealed a history disruptive dips at the plant with significant loss of production. Examination of the records showed that the plant was affected by faults in a wide area of the network; the objective of the study was to decide how to limit the exposure of the plant to these faults. The options for improvement include measures at the equipment, installation and network level. Several solutions are proposed and the cost of each estimated.
Electricity is all around us, it is a basic part of nature and a major source of energy. Electricity is used in homes and in industries We use electricity in our everyday lives to power all types of machinery and equipment, and to do all types of work. We use it for something as basic as powering the lights in our homes and workplaces. As such, it is not surprising that the largest consumers of electricity are residential homes in the U.S. According to the U.S. Energy Information Administration, 39.4% of electricity consumed in 2020 was by the residential sector, while the commercial sector consumption was 34.6% and the industrial sector consumed 25.8% (2021).
Regards, Mr. SYED HAIDER ABBAS
MOB. +92-300-2893683 MBA in progress, NEBOSH IGC, IOSH, HSRLI, NBCS,GI,FST,FOHSW,ISO 9001, 14001,
'BS OHSAS 18001, SAI 8000, Qualified .
Electrical Safety. Electrical hazards can cause burns, shocks and electrocution (death). Assume that all overhead wires are energized at lethal voltages. Never assume that a wire is safe to touch even if it is down or appears to be insulated.
Similar to Safety in non-residential electrical installations (20)
This Application Note describes the technology and applications of infrared heating. The basic principles behind the technology and its important characteristics, such as the effect of emissivity and shape coefficient on the rate of transfer of thermal energy, are described.
Infrared heating is characterized by high energy densities, rapid heating, and relative ease of installation. All these advantages offer the possibility of higher production speeds, more compact installations, and lower investment costs. Thus, in many industrial production processes, infrared heating offers advantages with respect to conventional heating techniques such as convection or hot air ovens.
Induction heating is used for the direct heating of electrically conducting materials. The primary advantage is that the heat is generated within the material itself, giving very fast cycle times, high efficiency, and the potential for localized heating. On the downside, because of the desired coupling between inductor and load, there are restrictions on the size and geometry of the work piece. However, there are many applications in the field of heating or melting of metals.
This application note illustrates the use and advantages of dielectric heating, which as the name implies, is used for materials that are non-conducting. The essential advantage of dielectric heating is that the heat is generated within the material to be heated. In comparison with more conventional heating techniques (hot air, infrared, et cetera) in which the material is heated via the outer surface, dielectric heating is much more rapid. This is because electrical insulating materials, i.e. the domain of dielectric heating, are usually also poor conductors of heat.
Other interesting characteristics of radio frequency and microwave heating are the high power density and the potential for selectively heating materials. However, dielectric heating is an expensive technique and its application is generally limited to the heating of products with high added value, or to products that cannot be heated by other means.
Introduction to industrial electrical process heatingBruno De Wachter
This application note provides an introduction to a series of papers on industrial electric process heating technologies, hereinafter referred to as electro-heat or electro-heating technologies.
It briefly describes the basic principles of each of the various electro-heating technologies and explores their common ground. The economic and process related advantages of electro-heat are discussed. In the majority of cases, electro-heat has a better environmental performance than an industrial heating system utilizing natural gas or other fossil fuels. This application note provides some insight into why this is the case.
Finally, this paper provides an overview of the most appropriate applications as well as a short overview of the specific areas of technological development for each of the electro-heat technologies.
Life cycle costing (LCC) analysis helps you compare several investment opportunities based on the costs and revenues each investment generates over several years. You can learn how to perform a simple LCC in the application note "Life cycle costing (LCC): the basics".
Basic LCC is a good method for making informed decisions, but the outcome of such an analysis depends heavily on the quality of the input data and the assumptions you make. Energy prices, maintenance expenses, availability and discount rates are just some of the parameters you need to estimate. But it doesn’t stop there. You also need to able to defend your estimates. After all, each parameter can have a huge impact on your final decision. A critical audience, such as your management or funders, will undoubtedly test the robustness of your decision.
You can strengthen your case by including a sensitivity and risk analysis – in other words, perform a stochastic LCC analysis. It doesn’t necessarily require more or better information than a basic LCC analysis, but it does allow you to deal more effectively with the limited information at your disposal. A sensitivity analysis shows you how robust your decision is: in other words, would your choice between several investment opportunities change if any of the input parameters changed? A risk analysis shows you which risks you could manage to safeguard the profitability of your project.
This application note will teach you the basics of Monte Carlo Simulation, a powerful method that allows you to deal with risks and uncertainty by building and running a stochastic LCC model. Each step in the 5-step procedure is illustrated with a running example, which you can check yourself in MS Excel, using a free software add-in.
Many attractive investment projects – for instance in energy efficiency – are not carried out for various reasons (lack of capital, information, manpower…). Companies find it difficult to come up with a well-informed, satisfactory answer to the essential question: which projects are the most profitable in the long-term? What they need is a practical working method that is straightforward to use and produces reliable investment guidance. Life cycle costing is just such a method.
Life cycle costing (LCC) compares project cost estimates over the lifetime of a project. This application note shows how you can perform a rational LCC analysis by following a simple, 6-step procedure. The procedure uses common spreadsheet tools, so it’s time-efficient, and it teaches you how to derive numbers from a limited set of input variables, numbers that are good enough to make an informed decision.
The intention of this application note is to look at various aspects of generator sets (gensets) utilized globally to provide medium to long term backup power, and to improve system availability and reliability. Critical locations and applications depend on generators for back-up power. Examples of such critical locations are hospitals, airports, government buildings, telecommunications facilities, data centers, and nuclear power plants. Within this paper we intend to cover the main components of gensets, general applications, different fuels utilized, size selection, environmental issues, maintenance and noise pollution. The main emphasis of this document will be towards selection of gensets for critical loads and system availability.
This application note is intended to be a source of guidance and to help reduce confusion pertaining to the design, configuration, selection, sizing, and installation of Uninterruptable Power Supply (UPS) systems. This document is a useful information source for electrical consultants, electrical engineers, facility managers, and design and build contractors.
In the recent past, many design engineers have tried to create the perfect UPS solution for supporting critical loads. However, these designs have generally overlooked coverage for changing load profiles (e.g. leading power factor), sleep mode, and advanced scalability solutions. Such solutions and/or options can assist in gaining higher system efficiency, without exposing the critical load to disruptions from the utility.
This paper presents information related to various generic types of current UPS units, complete with their merits and demerits. It covers different topologies and various system solutions for clients. Auxiliary items, such as the battery bank, diesel generator set, and switchgear are included in the document since they also form an integral part of a UPS system.
To aid in the reduction of the carbon footprint, the paper has indicated achievable operational efficiency figures for different solutions.
A typical generic UPS Specification has been included as an Appendix to this paper to support electrical engineering professionals.
Replacement decisions for ageing physical assetsBruno De Wachter
The moment an asset will no longer be fit for use can seldom be determined when the asset is put in place. It invariably depends upon criticality and operational conditions. This is the reason there is a very large spread in useful asset life, even with the same type of assets within the same company.
Asset owners should periodically determine the remaining useful life (RUL) of their assets. An asset generally starts to deteriorate as it gets older. There are two main reasons why an organization needs to replace a deteriorated asset:
The operational costs (e.g. maintenance or energy costs) are rising to the point that it is economically better to invest in a new asset
The risk of critical failure is increasing to an unacceptable level
These are two different reasons that must be analyzed in two different ways.
A clear insight is necessary in the past and current costs of the asset, and in the age and condition of the asset, in order to correctly analyze the costs and to judge if replacement is economically a sound choice.
It is not possible, however, to use only past data to judge if the risk of continuing to use an asset is acceptable. Some critical failures could have such a significant impact that an organization should avoid them at all cost. For those assets, methodologies like criticality ranking and failure mode and effect analysis (FMEA) apply. Based on these, countermeasures and inspection programs can be put in place to mitigate the risks and determine when an asset should be replaced.
Developing preventive maintenance plans with RCMBruno De Wachter
Preventive maintenance has a great impact on performance, risk, costs and energy consumption of assets. It should be customised for each asset, because every asset works under different circumstances and has another criticality. One of the major shifts in point of view in preventive maintenance within these last few decades is that it should be aimed at fulfilling the organisational strategy.
Maintenance involves all the activities needed to keep an asset functioning according to the demands of the organisation. It includes not only overhauls or exchange of parts, but also calibration, inspection, cleaning, lubrication, functional tests and more. Simply replacing or restoring components after fixed intervals is called predetermined maintenance. This is often not an effective strategy, because only a minor part of all failure modes are time related. Most failure modes do not have a rising probability with rising component age. In these cases condition monitoring or function test may provide a good solution.
RCM is a good and generally accepted methodology to select preventive maintenance tasks. Because it is too time consuming to conduct it for every asset in an organisation, faster methods have been developed, such as Industrial RCM, which uses templates with failure modes and preventive maintenance actions for standard components.
This Application Note describes how to select the right mix of preventive maintenance tasks for an asset system, using RCM, Industrial RCM and Preventive Maintenance Set Up (PM Set Up).
Electrical storage systems: efficiency and lifetimeBruno De Wachter
This application note discusses the technical aspects of battery energy storage system design and operation and their influence upon system efficiency and lifetime. The various roles of electrical energy storage systems are discussed first in order to gain appreciation of the way these systems are used. This is followed by a discussion of the most common battery technologies and their aging mechanisms. Factors which affect the efficiency and lifetime of power electronics are also discussed, since power converter(s) and associated switchgear are essential elements and determine in part the performance of energy storage systems.
A common factor which affects both the lifetime of batteries and (power) electronics is heat: the higher the temperature, the faster a component ages. Energy losses result mostly in heat production. Striving for high energy efficiency in both the battery and power electronics thus gives a double payoff: in addition to the energy savings, the lowered heat production results in lowered cooling requirements and longer life of components due to a lower operating temperature.
Unleashing the limitless possibilities of electricity in technological applications requires proper caution and care. Handling vast amounts of energy—in any form—comes with significant hazards. When energy is released in an undesired way, the results can be devastating. One only needs to consider some manifestations of unwanted energy release in nature such as lightning strikes or earthquakes, to realize that handling energy requires due care.
Fortunately, the manifestation of energy in the form of electricity can be controlled—and thus can be made safe—relatively easily. Since its discovery, numerous methods and systems have been developed for harnessing electricity. This has enabled the benefits of electricity in everyday use and avoided its hazards.
The first section presents the most important and common hazards associated with the use of electricity, along with some basic concepts on hazard, risk, and risk reduction.
The second section gives an overview of common and standard design solutions, with a focus on the safety aspects of the particular techniques cited.
Cables that are exposed to fire while being expected to retain their functionality and provide power to essential equipment at another location must be appropriately selected and sized to take account of the increased electrical resistance at elevated temperature. Manufacturers offer cables and accessories that will survive a standard cellulose fire for 30, 60 or 90 minutes when correctly specified and installed.
Cables, including fire safety cables, are specified in terms that reflect their normal duty conditions; design parameters under fire conditions are rarely, if ever, specified. The objective of this paper is to provide a clear methodology for designing fire safety circuits based on the derivation and application of correction factors and standard cable parameters.
Cables that are exposed to fire while being expected to retain their functionality and provide power to essential equipment at another location must be appropriately selected and sized. This is not only a question of an appropriate insulation. Designers must take account of the increased electrical resistance at elevated temperature.
Manufacturers offer cables and accessories that will survive a standard cellulose fire for 30, 60 or 90 minutes when correctly specified and installed.
A first step to specifying a suitable fire safety cable is a good knowledge of the temperature rise characteristic in areas affected by the fire.
A second step is the correct selection and erection of the cable. This includes the correct sizing of the conductor. Cables, including fire safety cables, are specified in terms that reflect their normal duty conditions; design parameters under fire conditions are rarely, if ever, specified. The designer must take into account the consequent effects of the increased resistance on current carrying capacity, voltage drop, and short circuit capacity of the conductors. Special care should go to the current carrying capacity of the conductor if it is to supply electrically driven fire pumps drawing high starting currents. The circuit protection should also be adapted to fire conditions, as it must be designed to function with significant higher loop impedance than normal.
This paper provides a clear methodology for designing fire safety circuits based on the derivation and application of correction factors and standard cable parameters.
Having selected the appropriate cable, it must be installed properly, using suitable accessories and following the manufacturer’s restrictions.
Earth resistance is a key parameter in determining the efficiency of earthing systems. In this application note we look at the measurement of earth resistance.
After a description of some universal fundamentals (e.g. standards, error margins and the influence of the weather), various measurement methods are discussed. A common feature of all the methods is that they determine the earth impedance by measuring the voltage across the earthing system for a known test current. Apart from that, there is a wide degree of variation in the internal circuitry of the measuring instruments used and the layout and arrangement of the external measuring circuit. A major distinction can be made between methods that draw current directly from the supply, and those methods that don’t.
Each method has its own particular disadvantages such as limited applicability, electric shock hazard, larger measurement errors, or requiring more time and effort to complete. The various advantages and disadvantages of the individual measurement techniques are described in the final chapters of this application note.
The goal of energy management is similar to the Trias Energetica concept and aims to reduce energy waste, increase energy-efficiency of remaining energy consumers and increase the share of renewable energy. These days companies are confronted with ever more reasons to implement energy management: from legislative issues and stakeholder pressure to corporate vision and global competition. Energy costs money and represents risk and therefore needs to be properly managed.
Probably the biggest problem regarding energy consumption and its related costs is the so-called invisible nature of energy. Since electricity and gas always seem to be available yet usually not physically visible, people tend not to think about it and take energy for granted. This in turn explains the common lack of even a basic insight into the various streams of energy and their related costs. Logically, a lack of insight also leads to a lack of priority and/or commitment and to a lack of resources dedicated to addressing the issue. Nevertheless, more and more companies (especially multinationals in energy-intensive industries) have taken to implementing the international ISO50001 standard for energy management. In a similar manner to other quality system standards, this standard is aimed at structurally embedding energy management within the entire organization.
While a certified energy management system certainly has value, it may be overkill for many organizations. A simplified and pragmatic approach may even lead to quicker results and higher levels of enthusiasm among the staff. Management commitment however is a must, since resources will be needed to gain insight into the energy streams and to implement optimization projects. Understanding where, when, how much, why and at what cost energy is being consumed will require many people in various departments and functions to work together.
This application note discusses practical design of earthing electrodes, including the calculation of earthing resistance for various electrode configurations, the materials used for electrodes and their corrosion performance. Equations are given for many common electrode geometries, including horizontal strips, rods, meshes, cable screens and foundations.
Despite the fact that these formulae are derived under the false assumption that soil is boundless and homogenous and ignore the fact that the ground resistivity changes with moisture content, the values obtained, although approximate, are useful in predicting and optimising performance.
Fundamentals of electromagnetic compatibility (EMC)Bruno De Wachter
Electromagnetic interference, EMI, has become very important in the last few decades as the amount of electronic equipment in use has increased enormously. This has led to an increase in the sources of interference, e.g. digital equipment and switching power supplies, and an increase in the sensitivity of equipment to interference, due to higher data rates.
This development demands high quality electrical installations in all buildings where electromagnetic non-compatibility leads to either higher costs or to an unacceptable decrease in safety standards.
This application note gives an overview and a basic understanding of the major physical principles of electromagnetic interference and an introduction to the principles of mitigation of disturbing effects. As a result, the measures required to achieve an EMC-compliant installation should be easily understood.
Earthing systems: fundamentals of calculation and designBruno De Wachter
This application note discusses the principles of earthing electrode design with particular emphasis on earth potential distribution of various electrode geometries.
The electrical properties of the ground and variations according to type and moisture content are discussed. The equation for calculation of the earthing resistance and potential distribution for an idealized hemispherical earth electrode is derived. The concepts of step and touch voltages are discussed and the effect of earthing electrode geometry shown.
The concepts developed in this application note are the basis for the practical guidance given in Earthing systems: basic constructional aspects.
Behind-the-meter energy storage systems for renewables integrationBruno De Wachter
This paper explores renewables-linked behind-the-meter energy storage systems. It explores applications which can be performed with such systems, including the business model behind such applications and the duty cycle requirements of such applications. It also explores siting and technology choices, including battery types, inverter classifications and other purchasing and installation considerations.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...
Safety in non-residential electrical installations
1. APPLICATION NOTE
SAFETY IN NON-RESIDENTIAL ELECTRICAL
INSTALLATIONS
Paul De Potter
March 2016
ECI Publication No Cu0161
Available from www.leonardo-energy.org
3. Publication No Cu0161
Issue Date: March 2016
Page ii
CONTENTS
Summary ........................................................................................................................................................ 1
Introduction.................................................................................................................................................... 2
Designing a safe electrical installation ............................................................................................................ 4
Maintaining a safe electrical installation ........................................................................................................ 5
Initial inspection ............................................................................................................................................. 6
Periodic inspection ......................................................................................................................................... 6
Insulation resistance testing ........................................................................................................................... 7
Installation tester and other testers ............................................................................................................... 8
Good housekeeping........................................................................................................................................ 8
Thermographic inspection of electrical installations....................................................................................... 8
Training of the employees .............................................................................................................................. 9
Conclusion ...................................................................................................................................................... 9
4. Publication No Cu0161
Issue Date: March 2016
Page 1
SUMMARY
Statistics regarding electrical accidents worldwide indicate that thousands of people are injured or killed every
year. Electrical professionals working on the installation, maintenance, repair, and construction of electrical
facilities are in fact the very people most likely to experience an electrical accident. Of these, electricians are
the most vulnerable. Contact with electrical wiring or other electrical equipment is the most common cause of
an electrical accident.
Achieving a zero number of electrical accidents will require a safe electrical installation, properly maintained
over its lifetime, and an emphasis on the good condition of the measures protecting against electric shock and
burns. This, together with a proper training of employees, will go a long way towards achieving this goal.
5. Publication No Cu0161
Issue Date: March 2016
Page 2
INTRODUCTION
Life without electricity is unimaginable, not only in our daily lives at home, but also in the non-residential
sphere, the industrial workplaces, commercial business sites, office buildings, educational institutions, et
cetera.
We use electricity in virtually every aspect of our daily lives. We have grown both so dependent and at the
same time complacent that we seldom stop and think about it anymore. But we should not forget that we are
dealing with a potentially dangerous form of energy.
“Remember electricity can kill – unlike other hazards you cannot see, feel, hear or smell electricity
so there is no advance warning of danger.” (UK Health and Safety Executive)
Here is a reminder of a few of the well-known dangers:
- Muscle Contractions: It is sometimes impossible to let go of energized tools or equipment, thus
leading to a fatal accident. Even at safe current values below the let-go threshold, there can be a
sensation of shock and although not excessively painful, a person can react without thinking. In one
case, a man touched a mildly conductive part that had unexpectedly become live. He jerked away,
lost his balance, and fell to his death.
- Ventricular fibrillation: This is the rapid and irregular contraction of the heart muscle fibers caused by
disruption of nerve impulses. Death can occur quite rapidly.
- Electrocution: This is the general term for death caused by the passage of electricity through the body
(death caused by an electric shock).
- Shock (electric): This is the physical stimulation of trauma that occurs as a result of electric current
passing through the body. The symptoms of electric shock may include a mild tingling sensation,
violent muscle contractions, heart arrhythmia, and/ or tissue damage.
- Shock Circuit: This occurs when a strong electric current takes the most critical path through the
body. If the shock circuit involves critical organs, severe trauma is likely. The distribution of current
flow through the body is a function of the resistance of the various paths through which the current
flows.
- Electric Arc/Flash: This is the heat and light energy release that is caused by the electrical breakdown
of, and subsequent electrical discharge through, an electrical insulator, such as air.
- Arc energy input: The total amount of energy delivered by the power system to the arc. This energy
will be manifested in many forms including light, heat, and mechanical energy (pressure).
- Arc incident energy: Is the amount of energy delivered by an electric arc to the clothing or body of an
individual. The amount of energy will be somewhat less than the arc energy, based on factors at the
workplace.
- Blast (electric): This is the explosive effect caused by the sudden presence of an electric arc on the
rapid expansion of air and other vaporized materials that reach a superheated state.
- Burning: Burns caused by electric current are almost always third degree because the burning begins
on the inside of the body and moves outwards. This results in tissue growth centres being destroyed.
Electric-current burns can be especially severe when they involve vital internal organs.
- Fires of electrical origin: Excessive heating through arcing.
- Mechanical effects of short-circuits: If the currents in two adjacent conductors are flowing in
opposite directions, the conductors will try to separate from each other.
Before an electrically safe work condition exists, workers are exposed in many different ways to the hazards
associated with electrical energy:
6. Publication No Cu0161
Issue Date: March 2016
Page 3
- Electrical equipment, devices, and components all have a unique life expectancy. This results in control
devices sometimes malfunctioning. When a failure occurs, an electrical worker is expected to identify
the problem, repair the problem, and restore the equipment to normal service, thereby putting
themselves at some degree of risk.
- Electrical equipment must be properly maintained if it is to provide a normal or extended service life.
Although the electrical energy is generally removed before a worker begins a maintenance procedure,
such tasks often are executed while the source of electricity is energized.
- Equipment and circuits are sometimes modified to add new devices or circuits. Short-term employees
may not be aware of such modifications and unknowingly be expected to work in an environment that
includes exposure to energized electrical circuits and components. Consultant and service employees
are frequently exposed to energized electrical equipment and circuits.
- When a problem exists that causes equipment to operate in an abnormal manner, a worker may open
a door or remove a cover exposing an energized electrical conductor or component. In many cases,
the worker might troubleshoot while the circuit is energized. Attempts to add components and
conductors might be made while a piece of equipment or parts of the equipment remain energized.
- After correcting a problem, electrical workers sometimes inadvertently create further hazardous
conditions. This can occur from something as simple as leaving an equipment door ajar, failing to
close all latches, replacing covers with a minimum number of screws, and removing devices that leave
open penetrations through a door or wall.
The following are a few examples of accidents that have occurred in recent years:
- An electrician had to cut a cable that had to be replaced. He did not properly check to ensure that he
was cutting the correct cable. The wire cutter he was using had some damaged insulation. He was
sitting on a conductive part that was connected to earth. When he cut the first cable he touches a
phase and died instantly.
- While drilling a pit to make a connection, a worker touched a high voltage cable with his pneumatic
hammer. The ensuing arc causes severe burns on his hands and face.
Unfortunately, this list could go on for many pages. Apart from the obvious suffering that such accidents can
cause, they can also bring the business of the building owner in danger. If the electrical installation was not
properly installed and maintained, insurance companies will refuse to pay the requested financial
compensation.
It is known that an important role in the ignition of fires in buildings and structures is played by electrical
faults. Electrical fires can cause enormous damage and even the total destruction of property. Electrical faults
cause severe electro-mechanical forces, affecting insulation and damaging equipment and usually leading to
repairs and downtime. It is therefore of the utmost importance that electrical installations and electrical
equipment be constructed, erected, operated, and maintained as safely as possible. They must likewise remain
as safe as possible throughout their lifetime. This can best be assured by regular inspections and by following
the testing procedures recommended by the applicable electrical wiring regulations.
This paper is intended to address the importance of electrical safety in non-residential installations, but it is
obvious that electrical safety in residential installations is of utmost importance as well.
7. Publication No Cu0161
Issue Date: March 2016
Page 4
DESIGNING A SAFE ELECTRICAL INSTALLATION
Safety will be designed into an electrical installation if:
The latest editions of rules, codes and standards concerning electrical installations are followed
Any electrical equipment installed complies with relevant product standards
Strict pre-commissioning tests and visual inspections are carried out by a competent person
Periodic checking of the installation is carried out by a competent person
The main reference for good practice is the international standard IEC 60364 “Electrical installations of
buildings” and more particularly Parts 4 and 5:
- IEC 60364-1 Fundamental principles
- IEC 60364-4 Protection for safety
o IEC 60364-4-41 Protection against electric shock
o IEC 60364-4-42 Protection against thermal effects
o IEC 60364-4-43 Protection against overcurrent
o IEC 60364-4-44 Protection against electromagnetic and voltage disturbance
- IEC 60364-5 Selection and erection of electrical equipment
Most of the national electrical standards in the world (other than USA) are based on this standard.
Following IEC 60364 will ensure that:
- Safe materials and equipment are used.
- The materials and the equipment chosen are suitable to carry out the intended functions under all
possible external influences. It means that they are safe regardless of the influence of the
environment (temperature, water, dust, …), the habits and knowledge of the people using the
electrical installations (people who may or may not have been properly instructed about the dangers
of using electrical equipment and the electrical installation), the conditions in which these people
work (on grounded surfaces, in a basement, on an upper floor, …), the influence of the environment
on the fire hazard (flammable or explosive atmospheres, buildings that easily propagate fire,..)
- Protection against electrical shock by direct contact is assured by employing adequate insulation,
enclosures, and obstacles.
- Passive or active safety measures are used for protection against contact with parts which are
accidentally made live (indirect contact) – e.g. an automatic disconnect of power supply in the event
of an earth leakage fault.
- The protection against the thermal effects of the use of electricity is assured, taking into account the
type of materials processed or stored, the material used in the construction of the structures or
premises, the possibilities of evacuation, et cetera.
- Every part of the installation can be isolated in a safe way.
- Protection against burns and explosions is assured.
- Protection against over-currents (e.g. overload and short-circuit currents) is assured. (These are
currents that exceed the maximum that the protective device can interrupt without exploding or
starting a fire).
- Protection against overvoltage and switching surges, as well as lighting is assured.
- Electric cable risers/raceways in multi storied buildings are avoided. They can be a cause of fires that
can spread to other structural elements adjoining the cable routes. Metal enclosed bus bar trunking
systems must be used as vertical risers/horizontal raceways.
- And in general, that protective measures have been taken against all risks related to the use of
electricity.
8. Publication No Cu0161
Issue Date: March 2016
Page 5
MAINTAINING A SAFE ELECTRICAL INSTALLATION
Unfortunately, an electrical installation does not remain safe on its own. It will not retain its original condition
due to wear and tear on the equipment and ageing of the insulation. There can be damage, corrosion and
other effects.
Listed below are some of the most common faults found in electrical installations after a period of use:
- Loose contacts in conductors or other contact joints, termination failures (everywhere that
connections have been made—mainly in switchboards, panels, socket outlets, plug tops, and
electrical points).
- Damaged, punctured, or deteriorated cable insulation
- Oversized protective devices with regard to the designed/allowed current carrying capacity of the
conductor, taking into account the site conditions (ambient temperature, humidity), the wiring
method, and the presence of harmonics at the Point of Common Coupling (PCC).
- Circuit breakers that were replaced with the correct nominal current but with a short circuit current Isc
that is too low (no protection against maximum short circuit)
- Oversized protective devices with regard to the comparatively high earth fault loop impedance,
namely excessive length and smaller cross section of the circuit earth conductor used for the
protection against indirect contact
- Shunted fuses or circuit breakers set to high value
- Earth or ground connections loose or not put back after temporary disconnection
- RCDs not properly connected or even by-passed because of nuisance tripping
- RCDs connected in such a way that the test button cannot be used for regular periodical testing
- Excessive earth fault loop impedance (involving the risk that the over-current protective device is not
triggered in case of an earth fault)
- Live parts not properly protected against direct contact (e.g. missing covers)
- Protection against the spread of fire was not assured when additional cables were installed (no
adequate safety precautions and no correctly matched overcurrent protective device)
- Circuits that can no longer be properly identified and labels, notices, and other markings that have
gone missing or are incorrect
- Schematic wiring diagrams that are unavailable or not up-to-date
All of these defects can lead to serious consequences such as fires or fatal electrical accidents.
It is obvious that an electrical installation cannot be safe without maintenance. It is necessary to follow the
manufacturers’ instructions regarding the required maintenance in a strict manner (for instance on circuit
breakers, RCDs, or the replacement of deteriorated insulation). Since RCDs can detect most faults in an
electrical system and quickly switch off the supply, they must be properly installed, enclosed, tested and
protected against contamination and shock.
Periodic inspection and testing is absolutely necessary. Any deterioration of the installation that could impair
its safety must be detected by such inspections and testing. The user or maintenance team can decide to take
appropriate remedial actions by qualified electricians/repairmen. They must be well trained and should have a
proven experience in working on electrical installations and a proven knowledge of the rules and regulations of
the applicable standards.
How often is an inspection required? This will normally depend upon the type of installation, its use, its
frequency of maintenance, and the external influences in which it is operating. It can vary from annually for
electrical installations in hazardous areas (e.g. swimming pools or explosive atmospheres) to 3 or even 5 years
for certain types of office buildings.
9. Publication No Cu0161
Issue Date: March 2016
Page 6
During the refurbishment phase, accidents can happen. This risk can be minimized by:
Knowing the installation – verify the existing electrical drawings (if possible) and carry out a visual
inspection before starting refurbishment
A correct management of the “electrical project” to minimize the interruption time and reduce the
safety risk
Isolating the areas where refurbishment work may compromise safety
A ‘Safe System of Work’ designed by a competent person should be in place prior to commencement of work.
Properly trained and accredited electricians should carry out the work. They should be adequately informed
about the installations they are working on. Wherever possible, systems should not be ‘live’ when being
worked on and should not be restored to ‘live’ until everything has been installed correctly.
When using portable electrical equipment during refurbishment actions, electricians should remember that
Equipment designed for conventional domestic use is normally not suitable for the conditions found
during refurbishment
Cordless, low voltage equipment is safer by design
Electrical power tools should be regularly inspected and serviced by a competent person
INITIAL INSPECTION
An inspection must be carried out before an installation goes into service. This ensures that the installation
complies with the applicable electrical wiring rules, regulations, and standards, and that no mistakes were
made during its erection.
The aim of the initial verification is to determine whether the requirements of all the applicable prescriptions
have been met. This is achieved by inspection and testing as provided in IEC 60364. Before testing begins, it is
important that a full inspection of the complete installation is carried out. This is to confirm that the electrical
equipment and materials:
- Are in compliance with the safety requirements of the relevant equipment standards
- Have been correctly selected and erected according to the relevant rules and regulations and to the
manufacturer’s instructions, to ensure that performance is not adversely affected
- Are not visibly damaged
- Are suitable for the prevailing environmental conditions
After inspection, the following tests must be carried out:
- Continuity of conductors
- Insulation resistance of the electrical installation
- Protection by SELV, PELV, or by electrical separation
- Automatic disconnection of supply (tripping time of RCD Device)
- Measurement of the resistance of the earth electrode
- Measurement of the fault loop impedance
- Polarity, functional, and operational tests
- Voltage drop
PERIODIC INSPECTION
A periodic verification will primarily take into account the following:
10. Publication No Cu0161
Issue Date: March 2016
Page 7
- The measures to avoid contact between persons and electrically charged material
- More precisely, the adequacy of the earthing and bonding
- Whether each circuit is protected by a fuse or circuit breaker (verification if the overcurrent
protective device has not been tampered with, altered, or shunted)
- The measures to protect the system from shock, heat or damage
- The suitability of the switch gear and control gear
- The serviceability of the equipment (switches, socket-outlets, light fittings) by careful examination for
signs of overheating
- The condition of the wiring system (old types of cables, insulation of the cables)
- The provision of well-functioning RCDs
- The presence of adequate identification and notices
- The extent of any wear and tear, damage, or indications of overheating
- Changes in the use of the premises that can lead to deficiencies in the installation
As with the initial verification, it is necessary to carry out inspections, tests, and measurements. The
measurements will give a good indication of the soundness and fitness of the electrical installation and
particularly of the cables and contacts.
Some tests will have to be carried out without the supply connected, while others can only be performed with
the installation energized, for example:
- Continuity of the protective conductors
- Equipotential bonding
- Earth electrode resistance
- Earth-fault loop impedance
- Correct operation of the RCDs
- Correct operation of switches and isolators
Considering the importance of cables, contacts, joints and terminations in an electrical installation, the testing
of their soundness and fitness requires that tests be carried out without the supply connected.
INSULATION RESISTANCE TESTING
Principle: apply a stable continuous voltage for a defined period, measure the resulting current between the
two parts under test, and ascertain with Ohm’s Law that the insulation resistance is higher than the minimum
value required by the standards (usually greater than 1 M-ohm for a 230 V single phase AC circuit).
Measurements should be carried out with an insulation tester (Megger). An insulation tester used during the
initial verification will help to eliminate short-circuits or earth faults. During periodic verifications, the
insulation tester will also help to test the integrity of the cables by revealing insulation failures that could
result in shock and fire.
The test is executed between the active conductors (phase and neutral) and the PE (protective conductor)
connected to the earthing arrangement. For the purpose of this test, active conductors may be connected
together. The DC voltage applied between the live conductors (de-energized) and the earthing arrangement
will cause a negligible current to flow through the conductor and the insulation. The leakage current will
increase as the insulation continues to deteriorate.
An insulation resistance of less than 50 k-ohms means that a leakage current is flowing through the insulation
to the earth. This leakage current could shock an individual if there is no RCD or if there is an accidental
interruption of the protective earth conductor. A leakage current of 300 mA can generate enough heat to
ignite the surrounding materials, involving the risk of fire.
11. Publication No Cu0161
Issue Date: March 2016
Page 8
The insulation resistance of transformers, motors, generators, and cables should be regularly inspected to
detect deterioration of the insulation and to avoid electric shocks and breakdowns. Inspections should also be
done after the maintenance team has carried out repair work or when new cables have been installed.
INSTALLATION TESTER AND OTHER TESTERS
The installation tester, the earth loop impedance tester, the RCD tester, and the earth resistance tester are
good companions for every individual responsible for an electrical installation.
It can be used during the initial inspection and testing, during periodic inspections, and during fault finding.
It gives a good idea of the soundness and fitness of the installation by combining many functions, such as:
- Voltage measurement between L-N, L-PE and N-PE
- Earth resistance
- Equipotential bonding
- Insulation resistance
- Fault and line loop impedance
- RCD trip time and current
- Socket outlet test: earth connection, correct connections, polarity check
Some testers perform automatic test sequences and in many cases the results can be stored and be
transferred to a PC or a printer.
It is obvious that the person working with the installation tester or other testers need to be well trained; they
must not only ensure their own safety, but also the safety of other people around them. They should know the
installation and the standards that apply to that installation.
GOOD HOUSEKEEPING
When current flows through the electrical devices, heat is generated. Dust, dirt and poor ventilation can all
cause the device to be unable to give off its heat to the surroundings, which can result in fire. Good
housekeeping (removing dust from the switchboards and the cables, ensuring proper ventilation) can
eliminate many of those hazards.
THERMOGRAPHIC INSPECTION OF ELECTRICAL INSTALLATIONS
For a thermographic inspection there is no need to interrupt production. It is a non-contact inspection of
electrical installations under load. It will map the heat generated in an installation, cable or equipment.
When the temperature of the electrical component is very different from the nominal temperature, this may
be an indication that a defect exists or should be expected. Points susceptible to corrosion, oxidation, or dirt,
over-loaded cables, and bad contacts are made visible. Weak points can be detected before anything goes
seriously wrong (power loss and breakdown, overheating of the component, fire). Preventive maintenance and
repair actions can then be carried out.
It can also help in planning predictive maintenance, since thermographic inspection provides an accurate
status of the installation and indicates potential risks.
Thermographic inspections should be used more often to ensure the quality and safety of the installation.
Depending upon the environmental conditions and the load in the installation, the periodicity can be adapted.
This periodicity will also be influenced by the results of the latest inspections.
12. Publication No Cu0161
Issue Date: March 2016
Page 9
TRAINING OF THE EMPLOYEES
Employees should be informed of potential hazards and they should be trained to avoid them.
When installations and equipment comply with the relevant standards—and are thus considered safe—all
employees can use them. This does not eliminate the need to train the employees, to take care, and to always
follow safe work practices.
Whenever people have to work on, with, or near electrical installations, specific work practices have to be
followed. This applies to all electrical work as well as to all non-electrical work activities during which people
are exposed to electrical hazards (such as building work near overhead lines or underground cables). No one
should ever become complacent. You should always assume that electric circuits are energized unless you are
certain they are not. The right Personal Protective Equipment must be worn.
CONCLUSION
Although it is widely recognized that electricity is a potentially dangerous form of energy, there are still many
people injured every year from electrical accidents.
Everyone has a responsibility and a role to play in minimizing the number of electrical accidents:
Manufacturers making safe electrical equipment,
People writing and developing standards
Installers erecting well protected electrical installations
Inspectors carrying out correct inspections before putting an installation into service as well as
conducting periodic checks
Technicians maintaining the electrical installation in good condition
Employees using safe work practices so that they are not exposed to electrical hazards
Proper training for all people having to work on or near an electrical installation
Proper training for all people that have to work on or near an electrical installation must be provided. This is
the best guarantee for a safe work place without electrical accidents.
