Electric Power System Compatibility
Electronic Process Equipment
Copyright ” 1996 by the Institute of Electrical and Electronic Engineers, Inc.
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This is an unapproved draft of a proposed IEEE Standard, subject to change. Permission is hereby granted for IEEE Standards Committee participants to reproduce this document for purposes of IEEE standardization activities. Permission is also granted for member bodies and technical committees of ISO and IEC to reproduce this document for purposes of developing a national position. Other entities seeking permission to reproduce this document for these or other uses, must contact the IEEE Standards Department for the appropriate license. Use of information contained in this unapproved draft is at your own risk.
The proliferation of microprocessors and power electronics in commercial and industrial facilities has greatly increased the economic losses of power quality to business. There are no large scale studies on the cost of power quality to business. However, most industry experts believe that tens of billions of dollars (US) are lost each year in the USA alone due to inattention to compatibility. Before electronics invaded lighting, machine tools, heating and cooling equipment, power compatibility meant verifying the equipment nameplate voltage and frequency were consistent with the supply. Unfortunately, the electronics in todayís equipment that provide expanded features and flexibility demand more careful attention to its application with the power system.
The purpose of this document is to recommend a standard methodology for the technical and economic analysis of compatibility of process equipment with the electric power system.
This document does not intend to set performance limits for utility systems, power distribution systems, or electronic process equipment. Rather, it shows how the performance data for each of these entities can be analyzed to evaluate their compatibly in economic terms. The recommended methodology also provides standardization of methods, data, and performance of power systems and equipment in evaluating compatibility so that compatibility can be discussed from a common frame of reference.
The methodology is intended to be applied at the planning or design stage of a system where power supply and equipment choices are still flexible and incompatibilities can be resolved. The cost of trying to fix an incompatible system after installation is hundreds to thousands of times more than addressing it in the planning stage. Consequently, this document does not discuss troubleshooting or correcting existing power quality problems.
Since voltage sags present the greatest economic loss due to incompatibility, this first edition of the recommended practice develops a compatibility methodology specifically for voltage sags. However, compatibility encompasses many other issues such as harmonics, surges, radiated interference, etc. As better information is available on the environment/equipment response and experience is gained with this approach, compatibility methodologies will be developed for other issues. To aid the evaluation of the non-sag compatibility issues, a guideline list is included in section _. The guidelines present reasonable levels of performance of both the electrical environment and equipment for situations where downtime costs are high. These may be included in the purchase or service agreements for the electric utility and equipment supplier.
This recommended practice does not discuss technical options to improve compatibility. References and bibliographic listings provide detailed discussions of alternative methods. The alternatives are so numerous and process specific that such a listing would detract from the basic purpose of the document which is to plan for compatibility.
Clause 4 is the heart of the document and contains the work sheet used for evaluating compatibility. A completed worksheet provides the economic loss associated with the incompatibility of a particular system. The annexes provide the background and information necessary to apply the worksheet. They are the cost of equipment disruption, power system performance, and equipment performance. An example worksheet is also provided.