Electrical Safety
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Electrical Safety
The Following papers are from the 2013 Electrical Arc Flash Conference and Electrical Safety & Power System Protection Forum - Thanks to IDC Technologies.
Electrical Workplace Safety - Seven Electrical Safety Habits - Zarheer Jooma - Authored by Hugh Hoagland -This paper discusses seven electrical safety habits based on investigations of more than 150 electrical safety incidents and their the root causes.
The Dilemma of the Personal Protective Equipment Suppliers in Developing Countries - Ivan Pretorius Contracts Manager, Quality Safety - The dilemmas that suppliers find themselves in stem from the fact that they do not receive adequate information in order to meet their legal obligations regarding the supply of the correct Personal Protective Equipment. In order to assist in making this more user friendly for all concerned involves use of a simple Four Step Method which has proven to be very useful.
Properly Established Compliance Applications Provide Valuable Learning Platforms - Dr Donald Glass Engineering Consultant & Executive Director, St James Software - A number of facilities in North America have configured their Compliance Management applications together with other Operations Management applications (such as operations logbook, handover logbook, incident manager, hazard & root cause analysis) to provide a platform for continuous learning about the facility, the operations and the risk areas. An example of this approach can be observed in the linking a permit-to-work application with an operations management operation. The resultant, automatic escalation of high risk situations, combined with relevant information, allows the permit to work application to not only set a high standard - supporting the drive for high safety standards - but simultaneously help employees improve their skills while performing their duties. This paper examines how managers can use compliance programs to help with the training of new staff as well as with the streamlining of maintenance, safety and environmental programmes.
Electrical Safety for Engineers and Supervisors - A First Primer - Gary Triffitt - The purpose of this paper is to ensure that you, the audience, are made aware of the dangers and of modern practice in hazard management with particular reference to electricity.
Fault Reduction Strategy using Neutral Earth Resistor (NER) Installation - Cheng Lee - Lead Engineer, Peracon - Co-author : Frans Cloete, Peracon - Fault level reduction is an ongoing challenge in a growing electrical network. With generation and network capacity continually being added to the system, the fault levels in various locations of a distribution network will soon approach their maximum allowable design level. For electrical power distribution companies there are a number of business drivers that force the implementation of fault level reduction schemes. While the general operation of Neutral Earthing Resistors (NER) for fault level reduction is well understood, optimisation of the design under various network configurations to yield maximum benefit requires detailed study. This paper presents the studies carried out in assessing the impact of Neutral Earthing Impedances of varying sizes for phase-ground faults on a “generic” network with three different configurations: Delta-Star Transformer configuration; Star-Star Transformer configuration; and Bus Tie CB Open (Delta-star Transformer configuration) The impact of Transient Recovery Overvoltage (TRV) on selected zone substation configuration resulting from the installation of NERs is also presented.
Arc Flash
Evaluation of Arc Flash Hazards Using Computer Based Simulation - Hilton Bennie - Senior Electrical Engineer, Applied Energy Solutions (Pty) Ltd - As engineers are responsible for the safety of personnel, it is our responsibility to perform the Arc Flash Hazard Analysis as accurately, yet conservatively, as possible. Being overly conservative may yield unnecessarily strict PPE requirements, which may be cumbersome and ultimately counter-productive. Engineers need to have tools and systems in place to ensure a high level of confidence in the results of the Arc Flash Analysis. We need the ability to perform our analyses on various scenarios, making sure that we account for the worst reasonable case.
Assessment and Selection of Arc Protective Performance of PPE - Go Beyond the Norms - Dr Helmut Eichinger -Technical Marketing Manager, Senior Consultant, DuPont International Operations, Geneva, Switzerland - The arc protective performance of PPE is usually expressed by its arc rating, typically its ATPV, evaluated according to ASTM, IEC or EN standards. Recent developments, findings and discussions suggest that more considerations should be given to further test result parameters (such as EBT, ELIM and/or Box test Class 1 and 2) and also that the understanding of the meaning of the test results with respect to probability of skin burns needs to be improved. Furthermore, there exist important performance assessment and selection aspects, which are not or only insufficiently dealt with in the existing norms, such as robustness of the arc protective performance as a function of laundering, wear conditions, contaminations, or such as wearer acceptance, aesthetics, comfort and heat stress, or whether and how to include underwear in the selection of appropriate arc protective PPE.
Calculating Arc and Incident Energy in an Arc Flash - Where do the Equations come from? - Prof Jerry Walker - Director, Walmet Technologies (Pty) Ltd - This paper gives a brief overview of the first formulas and methods developed since it was first recognised that Arc Flashes play a major role in electrical accidents, to the accepted methods and formulas used in present National and International Standards. It also highlights the deficiencies and constraints in the different methods. The formulas for the calculation of the incidence energy at a specific distance (arc flash boundary) are given but not discussed.
Grounded! - How to Deal with Arcing - Tommy Roes - UDT Business Unit Manager, Martec - Arcing is more common than we would like to believe, even in new installations. Detecting these defects can be challenging, particularly at an early stage. Not one inspection technique, can on its own, detect and localize every defect. Selecting the most appropriate method, requires that inspectors understand the nature of the defect and the signs and signals available to be detected. The next logical step is to have the right technology available to pin point their location. Discover the technologies and inspection techniques that should become mandatory for all electrical maintenance personnel. To not only reduce the risk of arc flash exposure, but also enhance the overall reliability of the electrical system. This paper discusses simple and practical solutions available for reducing Arc Flash related injuries or death, the obvious “front runner” in the “risk” department, and rightly so. Be that as it may, how far down the list do “loss of electrical assets” and “unplanned downtime” sit? The paper looks at a “win win” situation which will reduce the risk of all three.
Arc Flash Protection Study - Eskom Kendal Power Station - Linda Dlamini - Senior Portfolio Manager - TFMC and Moeketsi Melele - Senior Supervisor - Eskom PTM - Major strides have been made in understanding and preventing the undesirable consequences of arc flash incidents in the power utility. Fault level studies using some of the advanced software models, e.g. DigSilent and estimating incident energy and arc flash boundaries with some degree of accuracy using IEEE1584 model, are some of the greatest developments. Controlling exposure to arc flash is the last resort once the means to eliminate, or engineering means to reduce have all proven counterproductive or cost-ineffective. To achieve the right level of control, the solution of PPE has been implemented. This, together with other interventions to limit exposure to electric arc may significantly reduce the risk of exposure. The paper seeks to explain the studies leading to the decisions on Arc Flash PPE.
Development of Standards for MV Switchgear Rated for Arc Protection - Bryan Johnson - Product Group Manager, MV Switchgear, ABB South Africa - Switchgear standards historically considered the electrical capability of switchgear with little regard to the effects of internal arc. To achieve some degree of safety users and manufacturers have considered, measures ranging from PPE, specific operating procedures, through to remote control and arc detection systems, however these measures do not change the characteristics of the switchgear, and therefore the switchgear / switch room should still be considered a high risk area.
Arc Flash Protection - What More Can Be Done? - Laura Steenkamp - What more can be done to mitigate the risks of arc flash related injuries? This paper explores two aspects that already mitigate arc flash risks and poses questions as to why they may be less effective than anticipated. Why do fatalities still occur given the effort placed on proper procedures and clothing during switching? The paper also looks at the term ‘human error’ and what it means for the future of electrical arc safety.
Reducing Risk to Workers Using Infrared Windows - Steve Edwards - R&C Instrumentation - Temperatures can reach as high as 20000°C causing rapid expansion of hot air around the flash area. Copper Busbars vaporize and expand up to 67000times. A piece of copper Busbar the size of a pea becomes the size of a rail car. Molten copper now becomes hot shrapnel. This anomaly is asset destroying, unpredictable and if you are in its path it hurts. So, how can we make this safer? What about keeping the panel closed and doing the thermography through the closed panel? Impossible right? Wrong! A solution is available through the installation of infrared windows, which means the inspection can be carried out efficiently with the energised system enclosed behind a closed door. In fact, the installation of IR windows will not only make the inspection process safer, but will also save cost.
ROI Case Study 2 - Paper Mill Boosts RCM Program with Cost Savings Generated by its IR Window Program - Martin Robinson - Level 3 Thermographer, President & Chief Engineer, IRISS, inc. - A paper mill in Georgia had run a very successful infrared inspection program for a number of years using a local, contract thermographer working with the mill’s in-house electricians. Although the program had a good track record, senior management was concerned about the potential impact of NFPA 70E requirements, and how best to comply with them. The plant commissioned IRISS Inc. to conduct a cost-benefit analysis and present its recommendations.
Arc Flash - Safety by Design in LV Switchgear - David Stonebridge - ABB Australia - The Australian WH&S regulations & codes of practices have undergone dramatic changes in recent years. In 2012 the state & territory governments have to some degree harmonised the WH&S requirements, however when it comes to Arc Flash the debate continues with no firm national harmonised recommendations. Many mining companies in Australia have adopted the US regulations which have also undergone changes when it comes to protecting workers against Arc Flash. The focus of this paper is to look at safety by design in LV switchgear to protect workers against arc flash and to eliminate the need for PPE levels higher than category 2.
Internal Arc Safety in New and Existing Switchgear - Richard Blakeley - RPS SWITCHGEAR LIMITED - This paper highlights the issues in managing elderly oil-filled switchgear and explains the modes and consequences of failure of this equipment. It explains what happens when a ‘flashover’ occurs inside a switchboard and shows how the experiences of designing and testing switchgear to the latest standard for internal arc withstand can be successfully applied to existing switchboards to bring them in line with the latest requirements for internal arc safety.
Electrical Safety from the Ground Up - Proper Grounding and Bonding is Critical for Electrical Workplace Safety - Reza Tajali - Risks associated with shock and electrocutions from inadvertent contact with energized parts have long been recognized as a threat to electrical workers. In recent years, OSHA and industry associations recognized the severity and urgency of the situation which resulted in the development of new standards for electrical workplace safety. In essence, they mandate that work on electrical equipment must be performed in a manner that does not expose the worker to undue risk of injury. While arc flash awareness has been growing (as well it should), the dangers of shock and electrocution should not be overlooked. In fact, electrocution is the second leading cause of construction site fatalities in the US. In an average eight-hour day, 16 workers require time off the job to recover due to electrically induced injuries - from Schneider Electric Engineering Services and Plant Engineering.
Digital Substation
Movement to The Full Digital Substation for Primary Distribution - Albert Massoud - Automation Engineer & Account Manager, Alstom Grid - Digital devices such as numerical protection relays and digital control systems are prevalent in Substations today with a wide range of Technology being utilised. This article looks at other substation areas into which digital technology can permeate, such that progressively, substations can become fully digital in their implementation.
Evaluating Fire and Heat Damaged Electrical Equipment
NEMA Publishes Evaluating Fire- and Heat-Damaged Electrical Equipment - The National Electrical Manufacturers Association (NEMA) recently published Evaluating Fire and Heat-Damaged Electrical Equipment, a guide that provides information on how to evaluate electrical equipment that has been exposed to heat and fire residue through fire, firefighting activities, or close proximity to fire.This guide is useful for suppliers, installers, inspectors, and users of electrical products. Before this publication, little guidance was available for installers and inspectors on how to evaluate electrical equipment that has been exposed to heat and fire residue. Evaluating Fire and Heat-Damaged Electrical Equipment may be downloaded at no cost on the NEMA website.
IEC61850 Based Process Bus Protection Systems
IEC61850 Based Process Bus Protection Solution for Remote Located Power Transformers - Dinesh Mithanthaya - Design Manager, Horizon Power - This paper emphasises the use of an IEC61850 process bus based solution to meet all the protection requirements of transformers. The sensitivity, selectivity, stability, speed and reliability of the scheme can be achieved, by using a single unit protection relay, with the electrical secondary parameters converted to digital data at the switchyard equipment, and transported through fibre link, with no electrical interference or cable burden issues. It is a neat and clean solution, easy to install and maintain, leading to cost benefit to the user.
Power Transformers
An On-Line Technique to Detect Winding Deformation within Power Transformers - A. Abu-Siada - Senior Lecturer, Curtin University - Frequency Response Analysis (FRA) has been growing in popularity in recent times as a tool to detect mechanical deformation within power transformers. To conduct the test, the transformer has to be taken out of service which may cause interruption to the electricity grid. Moreover, because FRA relies on graphical analysis, it calls for an expert person to analyse the results as so far, there is no standard code for FRA interpretation worldwide. In this paper an online technique is introduced to detect the internal faults within a power transformer by considering the voltage-current (V-I) locus diagram as a transformer fingerprint that can be measured every cycle to provide a current state of the transformer. The technique does not call for any special equipment as it uses the existing metering devices attached to any power transformer to monitor the input voltage, output voltage and the input current at the power frequency and hence online monitoring can be realised. Various types of faults have been simulated to assess its impact on the proposed locus. A Matlab code based on digital image processing is developed to calculate any deviation of the V-I locus with respect to the reference one and to identify the type of fault. The proposed technique is easy to implement and automated so that the requirement for expert personnel can be eliminated.
Transmission Power Transformers
Condenser Construction and Awareness of Negative Power Factor on Dielectric Dissipation Factor (DDF) Measurements - Wayne Proud - Technical Officer, Westernpower - As an owner of Transmission High Voltage transformers you will want to manage your plant on condition. One of the accessories of a Transmission Power Transformers is the bushings. A failure of this accessory will lead to a loss of supply from this asset and may even result in a transformer fire which would not only destroy the Transformer, but it may lead to the destruction of neighbouring plant. As an Asset Manager you will have a need to reliably measure the capacitance and Dielectric Dissipation factor (DDF) of the bushings to monitor their condition. As quality control results needs to be accurate and reliable, inconsistencies can lead to poor evaluation and premature replacement. This paper discusses the principals of condenser construction related to testing bushings and presents a case study of the phenomenon of negative results associated with DDF measurements which could influence trending.