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The standard for electrical safety in the workplace, National Fire Protection Association 70E, and relevant Occupational Safety and Health Act electrical safety standards evolved in the U.S. over the past 40 years to address the hazards of 60-Hz power that are faced primarily by electricians, linemen, and others performing facility and utility work. This leaves a substantial gap in the management of other types of electrical hazards including battery banks, dc power systems, capacitor banks, and solar power systems. Although many of these systems are fed by 50/60-Hz energy, we find substantial use of electrical energy, and the use of capacitors, inductors, batteries, solar, and radiofrequency (RF) power. The electrical hazards of these forms of electricity and their systems are different than for 50/60 Hz ac power. At the IEEE Electrical Safety Workshop in 2009, we presented a comprehensive approach to classifying the electrical shock hazards of all types of electricity, including various waveforms and various types of sources of electrical energy. That paper introduced a new comprehensive electrical shock hazard classification system that used a combination of voltage, shock current available, fault current available, power, energy, and waveform to classify all forms of electrical hazards with a focus on the shock hazard. That paper was based on research conducted over the past 100 years and on decades of experience. This paper continues the effort in understanding and managing all forms of injury from all forms of electricity with the introduction of a comprehensive approach to classifying all forms of injury from the electrical arc, including thermal, blast pressure, hearing, radiation, and shrapnel injury. The general term “arc” is divided into the arc, arc flash, and arc blast as a first subdivision of type of source of injury. Then, the parameters of voltage, short-circuit current, energy, waveform, gap distance, gap geometry, enclosure geometry, and time are used to choose various approaches to analysis. Recent efforts to understand, model, and estimate injury for these types of systems are reviewed. Most of the focus to understand and predict injury for dc, capacitor, solar, and RF arc hazards has been only in the past 10 years. A comprehensive approach to analyzing all forms of injury from all forms of electrical arcs is presented. [ABSTRACT FROM AUTHOR]

For the past decade, the discussion of occupational electrical safety in the U.S. has largely focused on compliance with NFPA70E, Standard for Electrical Safety in the Workplace. Without taking away from the importance of the requirements in the standard, this paper describes a more comprehensive solution, based on proven concepts derived from systems safety engineering. This paper provides an overview of systems safety engineering and includes a 20 $+$ year case history of a global Fortune 500 company's effort to change the electrical safety culture in its operations to demonstrate results of applying systems safety techniques to electrical safety. [ABSTRACT FROM PUBLISHER]

Microinverter-based photovoltaic (PV) systems now represent about 8% of the U.S. residential market, and offer many advantages including safety, performance, and simplified installation. The next-generation of PV microinverter will include more ancillary functions to support grid stability and reliability in more distributed generation smart-grid systems. A commercial ready PV microinverter not only focuses on efficiency and cost, but also on reliability, manufacturability, compliance of various grid-code, and electromagnetic interference regulations. This paper presents a detailed design and development process of a microinverter system from concept all the way to final commercial-ready prototype. Various design tradeoffs such as topology, control, filter solutions and power supplies, and mechanical packaging are provided. The required prototype testing and final system field tests are also presented. The presented design and test process intends to accelerate the future microinverter system design and development toward a commercial ready product. [ABSTRACT FROM PUBLISHER]

Today's power utilities, around the world, own multiple substations that are connected together to form a complex energy network. The functions within and between these substations are being automated according to globally accepted power utility automation standard IEC 61850. This automation results in efficient operation and enhanced protection of power network with the aid of the communication system. Implementing the protection schemes modeled using communication configurations of standardized information exchange will lead to digital power grid. Designing an IEC-61850-based protection scheme to take care of the faults outside the substations is a challenge, as the typical local-area-network-based generic-object-oriented substation events and sampled-value messages need to be transmitted over a wide-area network. This paper presents communication configuration for line current differential protection schemes applied between two automated substations. It presents the simulation results of communication configuration network between two substations. Its performance is evaluated using a network simulator tool. This study intends to guide the development of a robust protection scheme with IEC-61850-based communication configuration. [ABSTRACT FROM PUBLISHER]

In the context of the hierarchy of risk controls, warnings, administrative controls, and personal protective equipment are sometimes referred to as lower order controls. In practice, the effectiveness of these controls can be overestimated due to a misunderstanding of the human factors that affect error likelihood in their implementation. This paper explores one human factor: the limitation of attention on residual risk inherent in lower order controls. The limitation of attention has implications for identifying hazards, assessing risk, taking appropriate actions based on warnings, executing safe work practices, and proper selection and use of personal protective equipment. Raising awareness and improved understanding of these topics can enable more effective risk assessment, quantification of residual risk, and more effective selection and combination of risk controls to achieve risk as low as reasonably practicable. [ABSTRACT FROM PUBLISHER]

Energy efficiency policies require the implementation of strategies to reduce energy use during the operation of integrated urban water systems. In Italy, the overall amount of electrical energy consumption for water systems is close to 2.3% of the total national consumption, thus efforts to minimize costs are crucial. This paper analyzes a case study of urban water systems in a specific area in the Piedmont Region, Italy; the case study includes the data collection methodology and the analysis of the energy consumption of seven large water providers. The discussion includes the quantification of the energy consumption reduction, achievable with the replacement of existing transformers with high-efficiency transformers, power factor correction, and the use of variable-frequency drives for the centrifugal pumps. [ABSTRACT FROM PUBLISHER]

Load participation is vital for the smart grid development. As an effective tool to improve reliability, stability, and financial efficiency of the power grids, demand response (DR) has brought significant financial and technical benefits to power systems. As one of the price-based DR programs with less control costs, the time-of-use (TOU) program has been applied as the default rate structure by many utility companies. To avoid financial risks and make the most profit from the market, utility companies treat TOU as an effective strategy to change customers’ electricity consumption patterns. As reported in many literature, existing TOU programs are not as effective as expected in many developed countries due to the complexity of human behaviors and disparities of residential customers. To examine whether to obtain different outcomes of TOU on the residential customers in developing countries, actual utility usage data from residential consumers in Shanghai, China, are analyzed in this paper. The result shows current TOU in Shanghai, China, has similar trends as TOU in developed countries. With high penetration level of renewable energy, an effective TOU program is urgently needed in the utility industry. In recent years, a creative TOU pricing structure has been introduced at the Electrical Reliability Council of Texas deregulated market, and it shows that the introduced “zero pricing” strategy has a significant impact on customers’ consumption patterns. The purpose of this research is to examine the key reasons that underlie ineffectiveness/effectiveness of TOU programs at residential level. [ABSTRACT FROM PUBLISHER]

In spite of the names of “building attachments” and “secondary elements” usually given to nonstructural components and equipment, they are far from being secondary in importance. In the worst case of critical facilities, the failure of equipment strongly impacts on the postearthquake functionality, causing the loss of essential services or businesses. Such considerations highlight the need for a seismic qualification of equipment as the essential means to demonstrate its adequacy to perform the required function during the expected earthquake event. In this paper, the authors deal with a new approach to the problem of seismic qualification, in which the seismic demand posed to the component is defined in terms of equipment seismic levels (ESLs), whereas its inherent seismic capacity is classified in terms of equipment qualification categories. The determination of the ESL, which is the subject of this paper, has to satisfy the requirements prescribed by the codes for the seismic design of equipment. A comparative study of the current seismic codes in the USA and in Europe is hence carried out in order to critically assess their provisions and to develop a methodology that can be implemented straightforwardly also by designers not having expertise in the field of earthquake engineering. [ABSTRACT FROM PUBLISHER]

A significant amount of green power is being installed at the distribution level through the installation of green power generation facilities in the U.S. and Canada. This paper discusses green-power-generating sources (of 10 MW or less), which are connected to the utility system at the distribution level, and their impact on the distribution system. This paper also discusses the impact of smart grid and whether this new technology can solve some of the issues raised in this paper. Distribution circuits are designed to supply radial loads. Therefore, the introduction of green generation could mean redistribution of fault and load currents on the feeder circuit, overvoltage, and ferroresonance, plus a possible loss of protection system coordination—all of which can result in customer outages. This paper discusses these issues which are generally not well understood by many distribution protection engineers and can adversely affect distribution system reliability. [ABSTRACT FROM PUBLISHER]

This paper discusses historical and technical events in the U.S. and Europe over the last few years that are aimed at modernizing the electric power grid. The U.S. federal government has ratified the “smart grid initiative” as the official policy for modernizing the electricity grid including unprecedented provisions for timely information and control options to consumers and deployment of “smart” technologies. European countries are unified in researching and developing related technologies through various structures supported by the European Union. This paper presents the development of smart grids and an analysis of the methodologies, milestones, and expected evolutions of grid technologies that will transform society in the near future. [ABSTRACT FROM AUTHOR]

This paper presents a sensitivity analysis of similar days (SD) parameters to increase the accuracy of artificial neural network (ANN) and SD-based short-term price forecasting. Work presented in this paper is an extended version of previous works done by the authors to integrate ANN and SD method for predicting electricity price. The focus here is on sensitivity analysis of SD parameters while keeping the parameters same for ANN to forecast hourly electricity prices in the Pennsylvania--New Jersey--Maryland (PJM) (regional transmission organization in northeast America) electricity market. Several cases are simulated by choosing (a) two, (b) three, (c) four, and (d) five SD parameters to calculate the norm. In addition, sensitivity analysis has been carried out by changing the time framework of SD (d = 15,30, 45, 60) and the number of selected similar price days (N = 5, 10). From sensitivity analysis, it is identified that the optimized mean absolute percentage error (MAPE) is obtained using case-c with d = 30 and N = 10. MAPE of reasonably small value, along with forecast mean square error and mean absolute error of around 2$/MWh and 1$/MWh, is obtained for the PJM data, which has correlation coefficient of determination (R²) of 0.7758 between load and electricity price. Numerical results show that forecasts generated by the developed ANN model based on the optimized case are accurate and efficient. [ABSTRACT FROM AUTHOR]

In a power system covering a large geographical area, a single model for load forecasting of the entire area sometimes cannot guarantee satisfactory forecasting accuracy. One of the major reasons is because of the load diversity, usually caused by weather diversity, throughout the area. Multiregion load forecasting will be a feasible and effective solution to generate more accurate forecasting results, as well as provide regional forecasts for the utilities. However, a major challenge is how to optimally partition/merge the areas according to the regional load and weather conditions. This paper investigates the electricity demand and weather data from an electric utility in Midwest, U.S. Based on the data analysis, we demonstrate the existence of weather and load diversity within its control area and then develop a short-term multiregion load forecasting system based on support vector regression for day-ahead operation and market. The proposed multiregion forecasting system can find the optimal region partition under diverse weather and load conditions and finally achieve more accurate forecasts for aggregated system load. The proposed forecasting system has been tested by using the real data from the system. The numerical results obtained for different region partition schemes validate the effectiveness of the proposed multiregion forecasting system. The detailed discussions on the forecasting results have also been given in this paper. [ABSTRACT FROM AUTHOR]

Short-term load forecasting is always a popular topic in the electric power industry because of its essentiality in energy system planning and operation. In the deregulated power system, an improvement of a few percentages in the prediction accuracy would bring benefits worth of millions of dollars, which makes load forecasting become more important than ever before. This paper focuses on the short-term load forecasting for a power system in the U.S., where several alternative meteorological forecasts are available from different commercial weather services. To effectively take advantage of the alternative meteorological predictions in the load forecasting system, a new comprehensive forecasting methodology has been proposed in this paper. Specifically, combining forecasting using adaptive coefficients is applied to share the strength of the different temperature forecasts in the first stage, and then, ensemble neural networks have been used to improve the model's generalization performance based on bagging. The proposed load forecasting system has been verified by using the real data from the utility. A range of comparisons with different forecasting models have been conducted. The forecasting results demonstrate the superiority of the proposed methodology. [ABSTRACT FROM AUTHOR]

Ocean energy conversion systems have recently seen renewed interest, stimulated mostly by today's increasing energy discussions. In addition to ocean current energy converters, several commercial ocean wave energy projects have already been undertaken; however, no clear economic model exists for developers to follow. Therefore, this paper focuses on U.S. economic factors that affect the use of wave power for generation of electric energy. These are addressed with regard to economic and business incentives for renewables and wave energy. This paper also investigates incentive programs needed to promote wave energy conversion technology. [ABSTRACT FROM AUTHOR]

A very popular method utilized in quantifying the benefit of power delivery service reliability is to estimate the customer monetary losses associated with power supply interruptions by collecting data with customer surveys. MidAmerican Energy Company, a Midwest utility, recently performed surveys of its customers in the residential, commercial, industrial, and company/organization sectors. This paper presents the industrial and commercial customer results of these surveys with primary focus on the cost results. The results of this paper are compared with the results of other studies performed in high-cost areas of the United States' east and west coasts. This is the first ever paper of this nature performed for the electrical customers in the United States' Midwest region. Methodological differences in study design compared with coastal surveys are discussed. The major contribution of this paper is that particulars of Midwest customers compared with customers of coastal utilities are noted, the impact on customers with backup supply is identified, a suggested approach to enhance customer satisfaction due to advance warning on outages is recommended, and relatively high survey response return rates are elaborated. The customer damage functions derived from the survey results are being routinely used in power delivery project justifications in annual delivery system budgeting processes. [ABSTRACT FROM AUTHOR]

This paper updates an earlier report by the authors that studied electrical injuries from 1992 to 1998. The previous information is expanded and supplemented with fatal and nonfatal injury rates and trends through 2002. Injury numbers and rates were used to compare and trend electrical injury experience for various groups and categories. This information allowed identification of at-risk groups that could most benefit from effective electrical safety interventions. The data presented in this paper are derived from the U.S. Labor Department's Bureau of Labor Statistics' Census of Fatal Occupational Injuries, Survey of Occupational Illnesses and Injuries, and Current Population Survey. Between 1992 and 2002, 3378 workers died from on-the-job electrical injuries. Electricity remained the sixth leading cause of injury-related occupational death. From 1999 to 2002, 4.7% of all occupational deaths were caused by electricity, down from 5.2% in the 1992-1998 time period. The cause of death was listed as electrocution in 99.1% of fatal cases. Contact with overhead power lines was involved in 42% of all on-the-job electrical deaths. The construction industry accounted for 47% of all electrical deaths between 1992 and 2002 but showed overall improvement from 1995 to 2002 by reducing its electrical fatality rate from 2.2 to 1.5 per 100 000 workers. In addition, 46 598 workers were nonfatally injured by electricity. Contact with electric current of machine, tool, appliance, or light fixture and contact with wiring, transformers, or other electrical components accounted for 36% and 34% of nonfatal electrical injuries, respectively. Contact with underground buried power lines was involved with 1% of fatal injuries and 2% of nonfatal injuries. The research of the National Institute for Occupational Safety and Health aimed at evaluating commercially available overhead power line proximity warning alarms is described. This paper is expected to be the initial step for eventual development of a performance standard for such systems. [ABSTRACT FROM AUTHOR]

This paper discusses power-system instability and the importance of fast fault-clearing performance to aid in reliable production of power. An explanation regarding small-signal stability, high-impedance transmission lines, line loading, and high-gain fast-acting excitation systems is provided. Transient stability is discussed, including synchronizing and damping torques. The power-angle curve is used to illustrate how fault-clearing time and high initial response excitation systems can affect transient stability. The term "power-system stability" has become increasingly popular in generation and transmission. The sudden requirement for power-system stabilizers (PSSs) has created confusion about their applicability, purpose, and benefit to the system. This paper discusses the fundamentals of the PSS and its effectiveness. In today's paper industry, PSSs are being applied on larger machines in the northwest United States and Canada. [ABSTRACT FROM AUTHOR]

Condition monitoring of electric motors avoids severe economical losses resulting from unexpected motor failures and greatly improves the system reliability and maintainability. Efficiency estimation, which shares many common requirements with condition monitoring in terms of data collections, is expected to be implemented in an integrated product. This brings more considerations into the selection of the efficiency-estimation methods. This paper presents the results of an up-to-date literature survey on efficiency-estimation methods of in-service motors, particularly with considerations of the motor-condition-monitoring requirements. More than 20 of the most commonly used methods are briefly described and classified into nine categories according to their physical properties. Six categories of these methods are more related to in-service testing and are compared in a table summarizing the required tests and measurements, intrusion level, and average accuracy. Estimation of the rotor speed and the stator resistance, the two stumbling blocks of various efficiency-estimation methods, is also carefully studied; commonly used methods are summarized. Based on the survey results, four efficiency-estimation methods are suggested as candidates for nonintrusive in-service motor-efficiency estimation and condition-monitoring applications. Another contribution of this paper is that a general approach for developing nonintrusive motor-efficiency-estimation methods is proposed, incorporating rotor speed, stator resistance, and no-load loss estimations. [ABSTRACT FROM AUTHOR]

The USA and Europe use different standards to provide electrical safety for employee workplaces. This paper examines the two standards NFPA70E and EN 50110, shows some of the similarities and differences, and looks at the possibilities for a gradual harmonization between the two systems. The paper would contribute to improve the electrical safety continuity in the worldwide globalization efforts. [ABSTRACT FROM AUTHOR]

Underground coal mines in the United States of America are required to install lifeline (LL) cable inside escapeways to guide miners out of a mine when visibility becomes poor due to heavy smoke. Some LLs consist of single or multiple steel conductors covered with a protective plastic outer layer. Research has shown that this type of LL can be a good conductor to guide a medium-frequency (MF) communication system signal to travel over large distances. To understand the MF propagation characteristics of an LL, National Institute for Occupational Safety and Health researchers took measurements on a section of LL in a coal mine, and obtained propagation parameters for analysis. The measurement data show that MF signals have a low attenuation which can enable the use of an LL for communication throughout a mine. The propagation parameters measured are presented in this paper. [ABSTRACT FROM AUTHOR]

The use of alternate fuels and raw materials in the cement manufacturing process has evolved substantially over the last two to three decades, along with approaches to acquire regulatory approval. Most recently, the Environmental Protection Agency (EPA) has published new regulations as an overlay to what has been in place, having the potential to significantly impact this practice. Instead of dealing with the state agencies that usually have permitting authority, the new rules add another layer of regulatory hurdles by EPA. The new regulations also force a more significant overlap of the air permitting and solid waste rules. As a result, implementing an alternate material program and seeking approval has the potential to be considerably more challenging for the regulated community, in addition to adding complexity for the state agency permitting staff. This paper provides an update on the latest solid waste and air regulations applicable to alternative material use in cement plants, and potential implications for the U.S. industry. Early experiences will be explored, in addition to contemplating potential permitting and/or approval pathways expected to be encountered with the newest regulations in place. [ABSTRACT FROM AUTHOR]

Common cause events are those specific groups of dependent events that might adversely affect the operation of a redundant system. Common cause failures (CCF) are considered a subset of dependent failures with a major difference that they cannot be explicitly modeled. A CCF is a single point of failure (SPOF) causing a unit and its “perceived” redundant unit to fail simultaneously. During the first few years of commercial nuclear power plant operations, many probability risk assessment (PRA) studies revealed that CCF have significantly contributed to core damages. Consequently, the U.S. Nuclear Regulation Commission (NRC) initiated various CCF analyses in the 1980s. Since then, CCF analyses have been synonymous with nuclear facilities, and a majority of CCF analysis efforts have rightfully been focused on the safety of nuclear plants. Given that many industrial and commercial mission-critical facilities and high-reliability organizations now require a high degree of availability, therefore, CCF cannot be ignored. The objectives of this paper are to present 1) the importance of considering CCF in reliability, availability, and maintainability (RAM) analysis for industrial and commercial mission-critical facilities and high-reliability organizations, 2) simple quantitative analysis methods of CCF for industrial and commercial mission-critical facilities, and 3) the need for including CCF as part of future failure data collection efforts. [ABSTRACT FROM AUTHOR]

Recent mine disasters in the U.S. exposed various inadequacies and gaps in mine-safety technology. Congress responded to these tragedies by enacting the Mine Improvement and New Emergency Response Act of 2006 (MINER Act), which resulted in the most significant change to mine-safety laws in 30 years. To help meet the requirements of the MINER Act and to help eliminate future tragedies, the National Institute for Occupational Safety and Health initiated aggressive research programs for developing new, and enhancing existing, mine-safety technologies. A major research emphasis addressed the lack of postaccident communications, which surfaced as a critical deficiency in some disasters. As a result, three communications approaches emerged as viable technologies—enhanced leaky-feeder, wireless-mesh, and medium-frequency systems. This paper describes the operation, application, advantages, and disadvantages of each system, as well as the challenges associated with underground wireless communications. [ABSTRACT FROM AUTHOR]

Electrical safety needs to be refocused. Over the last few years, there has been tremendous attention given to the arc flash hazard phenomenon. Even though this hazard needs attention to reduce the number of injuries occurring because of it, in some ways, it has become the predominate focus of electrical safety. Electrical safety is more than just the arc flash hazard. Electrical safety needs to be a holistic approach that includes all aspects of electrical safety. The Electrical Safety Program, which proved to be a good tool, is defined in NFPA 70E, Standard for Electrical Safety Requirements for Employee Workplaces. However, even this falls short of what is needed to make a step change in electrical safety performance. This paper will attempt to identify the voids in electrical safety and focus attention on the items that need to be addressed to take a more holistic approach to electrical safety. [ABSTRACT FROM AUTHOR]

The U.S. Navy is looking for methods to maximize the survivability of combat ships during battle conditions. A shipboard power distribution system is a stiff isolated power system that is vulnerable to voltage sags, which arise due to faults or pulsed loads, which can cause interruptions of critical loads. A series voltage injection type flywheel energy storage system (FESS) is used to mitigate voltage sags and maximize the survivability of the ship. The basic circuit consists of an energy storage system, power electronic interface, and a series injection transformer. In this case, the energy storage system consists of a flywheel coupled to an induction machine. The stored energy is used for sag correction for the critical load. Indirect field-oriented control (IDFOC) with space-vector pulsewidth modulation (SVPWM) is used to control the induction machine. Sinusoidal PWM is used for controlling the power system side converter. This paper presents the modeling, simulation, and analysis of a FESS with a power converter interface using PSCADIEMTDC. [ABSTRACT FROM AUTHOR]

Industrial distribution systems have been designed in the USA, considering prevalent standards, i.e., American National Standards Institute (ANSI), IEEE, National Electrical Code (NEC), Occupational Safety and Health Administration (OSHA), etc., and arc flash was not a consideration for designing electrical power systems in the industry. Functionality and economics were the important factors, and will always be so. However, the arc flash analysis and limiting the incident energy will usher a new parameter in system design. It can be demonstrated that in many current installations and new installations designed without considerations of limiting the arc flash energy, the hazard risk category exceeds the highest Class 4 personal protective equipment (PPE), i.e., an arc thermal performance exposure value (ATPV) of 40 cal/cm². This paper discusses typical industrial distribution systems at low-voltage and medium-voltage levels and demonstrates the impact of system design decisions and protection on the incident energy and arc flash hazard reduction. [ABSTRACT FROM AUTHOR]

Following the steps of the gas industry, the traditional paradigm of the vertically integrated electrical utility structure has begun to change. In the United States, the Federal Energy Regulatory Commission has issued several rules and Notices of Proposed Rulemaking to set the road map for the utility deregulation. The crisis in California has drawn great attention and sparked intense discussion within the utility industry. One general conclusion is to rejuvenate the idea of integrated resource planning and promote the distributed generation via traditional or renewable generation facilities for the deregulated utility systems. Fuel cell and photo- voltaic are the most promising renewable generation technologies for the residential and small commercial users. It is desirable for these facilities to be interconnected with the utility grid to perform peak shaving, demand reduction, and to serve as emergency and standby power supply. However, the mismatch between the utility tie protection and the equipment protection makes it impossible for the fuel cell and/or photovoltaic to serve as emergency and standby power supply when the utility supply is lost due to nearby external faults. To overcome this issue, this paper discusses the development of an integrated high-speed Intelligent utility tie monitoring, control, and protection system to replace the traditional tie breakers for those residential and small commercial facilities with disbursed/renewable generation facilities. [ABSTRACT FROM AUTHOR]

Following in the steps of the gas industry, the traditional paradigm of the vertically integrated electric utility structure has begun to change. In the United States, the Federal Energy Regulatory Commission has issued several rules and Notices of Proposed Rulemaking to set the road map for the deregulated utility industry. The crisis in California has drawn great attention and sparked intense discussion within the utility industry. One general conclusion is to rejuvenate the idea of integrated resource planning and promote the distributed generation via traditional or renewable generation facilities for the deregulated utility systems. Wind generation is one of the most mature and cost-effective resources among different renewable energy technologies. Recently, several large-scale wind generation projects have been implemented in the U.S. and other parts of the world. Similar to other new generation facilities, the impacts of a large-scale wind generation on the system operation, voltage profile, and system security have to be investigated and studied. Remedies for possible operation issues have to be evaluated and implemented. This paper discusses the impact study of connecting a 120-MW wind farm into the transmission system of a utility company within the Southwest Power Pool. [ABSTRACT FROM AUTHOR]

Utilization voltages used on longwall equipment operating in coal mines in the United States have increased steadily over the past 15 years from 1000 up to 4160 V. This voltage in- crease has directly influenced the 200% gain in overall longwall productivity from 1987 to the present. The transition from medium voltage (661-1000 V) to high voltage (greater than 1000 V) has permitted significant increases in mining face widths and equipment sizes. Longwall systems with total connected loads of over 5000 hp are now common, and all longwalls in the United States now use high-voltage equipment, with the majority utilizing 4160 V. Shielded cables, which have significantly more capacitance than unshielded cables, are required for high-voltage applications in the mining industry. This capacitance can have detrimental influences on system overvoltages and relay selectivity during ground-fault conditions if the values for the neutral grounding resistor and the ground-fault-relay pickup settings are improperly chosen. These issues are addressed in this paper. [ABSTRACT FROM AUTHOR]

A significant banter to improving, the power quality at industrial facilities is the lack of contemporaneous and historical power quality and reliability data. A new Web-enabled near-real-time power quality and reliability monitoring system, termed 1-Grid, has been developed to provide such information on a nationwide basis. The ultralow-cost sensors record power events and send event data via the Internet to the system database servers using an internal modem. Data display, e-mail event notification, site administration, and summary reporting of the data are achieved via a Web browser. In cooperation with the U.S. Department of Energy, the Electric Power Research Institute, and leading utilities and manufacturers, the deployment of these sensors has begun, with a target deployment of 50 000 monitors across the U.S. and Canada over the next 2-4 years. This paper discusses the implementation of this grid information resource, and discusses data captured by the network since early monitors were deployed in 2001. [ABSTRACT FROM AUTHOR]