IEEE - The Institute of Electrical and Electronics Engineers@ Inc.
Scope
The design of reliable industrial and commercial power systems is of considerable interest to many people. Prior to 1962@ a qualitative viewpoint was taken when attempting to achieve this objective. The need for a quantitative approach was first recognized in the early 1960s when a small group of pioneers led by W. H. Dickinson organized an extensive AIEE survey of the reliability of electrical equipment in industrial plants. The AIEE survey that was taken in 1962 was followed by several IEEE reliability surveys@ which were published in 1973 through 1979. These surveys from the the 1970s were the basis for the reliability data contained in IEEE Std 493-1980. Six additional IEEE reliability surveys have been conducted and published during the 1980s and have been updated in this revision of IEEE Std 493-1997. The 1990 edition included pertinent tutorial reliability material and the cost of power interruptions data.IEEE Std 493-1997 presents two new chapters@ Chapter 9@ a new methodology for estimating the frequency of voltage sags at industrial and commercial sites@ and Chapter 10@ a methodology for estimating the number of tests required to demonstrate reliability of emergency and standby systems. New appendixes have been added on high- and low-voltage circuit breaker reliability data@ guarantees of gas turbines and combined cycle generating units@ transmission line and equipment outage data@ interruption costs@ and expectations for service reliability. The existing appendices have been updated.Tutorial reliability sessions on the design of industrial and commercial power systems were conducted at technical conferences of the IEEE Industry Applications Society in 1971@ 1976@ 1980@ and 1991.This recommended practice was prepared by a working group of the Power Systems Reliability Subcommittee@ Power Systems Engineering Committee@ Industrial and Commercial Power Systems Department of the IEEE Industry Application Society.This IEEE Recommended Practice serves as a companion publication to the following other Recommended Practices prepared by the IEEE Industrial and Commercial Power Systems Department:?? IEEE Std 141-1993@ IEEE Recommended Practice for Electric Power Distribution for Industrial Plants (IEEE Red Book).?? IEEE Std 142-1991@ IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems (IEEE Green Book).?? IEEE Std 241-1990@ IEEE Recommended Practice for Electric Power Systems in Commercial Buildings (IEEE Gray Book).?? IEEE Std 242-1986@ IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems (IEEE Buff Book).?? IEEE Std 399-1990@ IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis (IEEE Brown Book).?? IEEE Std 446-1995@ IEEE Recommended Practice for Emergency and Standby Power Systems for Industrial and Commercial Applications (IEEE Orange Book).?? IEEE Std 602-1996@ IEEE Recommended Practice for Electric Systems in Health Care Facilities (IEEE White Book).?? IEEE Std 739-1995@ IEEE Recommended Practice for Energy Management in Commercial and Industrial Facilities (IEEE Bronze Book).?? IEEE Std 1015-1997@ IEEE Recommended Practice for Applying Low-Voltage Circuit Breakers Used in Industrial and Commercial Power Systems (IEEE Blue Book).?? IEEE Std 1100-1992@ IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equipment (IEEE Emerald Book).The objective of this book is to present the fundamentals of reliability analysis applied to the planning and design of industrial and commercial electric power distribution systems. The intended audience for this material is primarily consulting engineers and plant electrical engineers.The design of reliable industrial and commercial power distribution systems is important because of the high cost associated with power outages. It is necessary to consider the cost of power outages when making design decisions for new power distribution systems as well as to have the ability to make quantitative ??cost-versus-reliability?? trade-off studies. The lack of credible data concerning equipment reliability and the cost of power outages has hindered engineers in making such studies.The authors of this book have attempted to provide sufficient information so that reliability analyses can be performed on power systems without requiring cross-references to other texts. Included are?? Basic concepts of reliability analysis by probability methods?? Fundamentals of power system reliability evaluation?? Economic evaluation of reliability?? Cost of power outage data?? Equipment reliability data?? Examples of reliability analysisIn addition@ discussion and information are provided on?? Emergency and standby power?? Electrical preventive maintenance?? Evaluating and improving reliability of existing facilitiesTwo new chapters have been added to this edition of IEEE Std 493:?? Chapter 9@Voltage sag analysis?? Chapter 10@ Reliability compliance testing for emergency and standby power systemsChapter 9 meets the demand for a methodology for estimating the frequency of voltage sags (which may interrupt processes and systems) at industrial and commercial sites. Chapter 10 presents a methodology for estimating the number of tests required to demonstrate reliability compliance of devices and systems while considering the reliability constraints dictated by the manufacturer and the customer.New appendixes have been added to IEEE Std 493@ and existing appendixes have been updated as follows:Appendix J@ ??Summary of CIGRE 13.06 Working Group Worldwide Reliability Data and Maintenance Cost Data on High Voltage Circuit Breakers Above 63 kV@?? contains a summary of the most significant reliability data and maintenance cost data from two CIGRE 13.06 Working Group worldwide reliability surveys of high-voltage circuit breakers rated 63 kV and above.Appendix M@ ??Reliability/Availability Guarantees of Gas Turbines and Combined Cycle Generating Units@?? contains one manufacturer??s suggestion on how to write a reliability/availability guarantee when industrial firms are purchasing gas turbine generating units or combined cycle units.Appendix N@ ??Transmission Line and Equipment Outage Data@?? contains the failure rates of transmission line equipment that can be used for predicting voltage sags at a particular industrial or commercial site caused by transmission line outages on adjacent feeders and/or from the entire electric network configuration.Appendix O@ ??Interruption Costs@ Consumer Satisfaction and Expectations for Service Reliability@?? presents a recent study on the cost of service interruptions to various industrial and commercial types. This data can be used for evaluating the cost-reliability worth of various industrial and commercial electrical configurations.Appendix P@ ??Survey Results of Low-Voltage Circuit Breakers as Found During Maintenance Testing@?? contains the results of a low-voltage circuit reliability survey achieved through the use of available results from testing during preventive maintenance.A quantitative reliability analysis includes making a disciplined evaluation of alternate power distribution system design choices. When costs of power outages at the various building and plant locations are factored into the evaluation@ the decisions can be based upon total owning cost over the useful life of the equipment rather than simply the first cost of the system. The material in this book should enable engineers to make more use of quantitative cost vs. reliability tradeoff studies during the design of industrial and commercial power systems.