ANSI IEEE 1050-2004 Guide for Instrumentation and Control Equipment Grounding in Generating Stations《发电站接地用装置和控制设备指南》.pdf
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1、IEEE Std 1050-2004(Revision of IEEE Std 1050-1996)1050TMIEEE Guide for Instrumentation andControl Equipment Grounding inGenerating Stations3 Park Avenue, New York, NY10016-5997, USAIEEE Power Engineering SocietySponsored by theEnergy Development and Power Generation Committee14 September 2005Print:
2、SH95270PDF: SS95270Recognized as anAmerican National Standard (ANSI)The Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USACopyright 2005 by the Institute of Electrical and Electronics Engineers, Inc.All rights reserved. Published 14 September 2005. Pri
3、nted in the United States of America.IEEE is a registered trademark in the U.S. Patent +1 978 750 8400. Permission to photocopy portions of any individual standard for educationalclassroom use can also be obtained through the Copyright Clearance Center.NOTEAttention is called to the possibility that
4、 implementation of this standard may require use of subjectmatter covered by patent rights. By publication of this standard, no position is taken with respect to the exist-ence or validity of any patent rights in connection therewith. The IEEE shall not be responsible for identifyingpatents for whic
5、h a license may be required by an IEEE standard or for conducting inquiries into the legal valid-ity or scope of those patents that are brought to its attention.Copyright 2005 IEEE. All rights reserved.iiiIntroductionThe original version of IEEE Std 1050 was published in 1989 after a five year devel
6、opment cycle. Specificrecommendations for the grounding of distributed control systems (DCS) were intentionally omitted fromthe 1989 edition since at the time the document was being written (19841987) there was not a large base ofinstalled systems and user experience on which to write a guide. Exper
7、ience since 1989 has shown that DCSgrounding is essentially no different from the concepts presented in the 1989 version, and would not requirea specialized treatment in the guide.The 1996 revision consisted of three major changes to the document. The first was the incorporation ofcomments, correcti
8、ons, and clarifications that have been brought to the attention of the working group. Thesecond change was a significant rearrangement of the document for enhanced user-friendliness. Thisincluded a complete redrawing of the significant figures in Clause 5 to more clearly depict the conceptsbeing ill
9、ustrated. The third change was the reformatting of the document to conform to the latest style man-ual for IEEE standards.The revision includes major improvements in terminology consistency along with further elaboration of thevarious concepts that are introduced. Additional enhancements have been m
10、ade to Clause 5 and its figuresfor clarity, including new subclauses on power source grounding and surge protection. Clause 6 on cableshields receives another reformatting to make the topics directly relate to the various types of I but their effects can becontrolled.b)Incidental sourcesThose caused
11、 by human activity; but they are not intentional.c)Intentional sourcesThese are emissions of potentially interfering energy produced for specificpurposes unrelated to the equipment or systems under consideration. 4.1.1 Natural sourcesProbably the most severe noise source to which any control system
12、will be exposed is lightning. While mostelectronic control systems will probably fail under a direct lightning strike, even a remote power line strikecan cause interference as the lightning-induced surge travels along power lines and is dissipated throughleakage, radiation, and power loss in the dis
13、tribution system.In addition to the currents created in the power systems conductors by a direct strike, lightning can also cre-ate similarly rapidly changing and high current flows through the earth and through numerous groundedmetallic systems and items such as cable shields, equipment grounding c
14、onductors, building steel, metallicpiping systems, conduits, raceways, and metallic equipment enclosures.Single-point grounding of the above metallic items does not prevent the indicated lightning current fromflowing because of the distributed capacitance of the involved items, which completes the c
15、urrent path viastray reactive coupling. In addition, insulation of these items is not always a reliable protection for this prob-lem since the large lightning induced voltages can often arc-over through six-feet of air.A typical lightning strike is composed of a downward-stepped leader stroke, usual
16、ly negatively charged, afirst upward positive return stroke, then two or more downward leader strokes, each followed by a positivereturn stroke. On average, subsequent strokes contain about 40% of the first strokes amplitude.IEEECONTROL EQUIPMENT GROUNDING IN GENERATING STATIONS Std 1050-2004Copyrig
17、ht 2005 IEEE. All rights reserved.7A continuing current is usually present between stroke sequences. There may be as many as twenty strokesequences in a typical lightning flash. Characteristics of a typical lightning flash are as follows:Potential 30 000 000 VPeak current 34 000 AMaximum di/dt 40 00
18、0 A/sTime interval between strokes 30 msContinuing current 140 AContinuing current duration 150 msAnalysis of the continuing current component of the lightning flash striking a power line indicates that itinitially behaves as a traveling wave and subsequently as a dc source. In cases where the light
19、ing stroke ter-minates on a tower or lightning terminal, it may be analyzed through circuit analysis.More information about the magnitudes and effects of lightning surge currents on structures, electrical sys-tems, building wiring, and telecommunications system cables may be obtained by reference to
20、 IEEE Std1100-1999, IEEE Std C62.23-1995, IEEE Std C62.41-1991 (R1995), IEEE Std C62.43-1999, NFPA-780-1997, and IEC/TR 61312-1:1995.4.1.2 Incidental sourcesSince one of the largest potential sources of electrical noise in an electrical generating station is the adjacenthigh-voltage substation, some
21、 of the incidental sources mentioned in the following subclauses originate pre-dominantly in the substation environment. Experience has shown that the electrical noise generated in thepower distribution system may reach the generating station I therefore, when the ESDstrikes the external surface, it
22、s wavefront also travels through the thickness of the door or panel and is re-radiated from the inside surface into the enclosures volume containing the ESD susceptible circuits.IEEECONTROL EQUIPMENT GROUNDING IN GENERATING STATIONS Std 1050-2004Copyright 2005 IEEE. All rights reserved. 15An example
23、 of ESD would be a 5000 V, 5 A current pulse of 200 ns duration. While the energy contained inthis pulse is only about 1.25 mJ, this is sufficient to interfere with computer logic levels. An arc dischargedoes not have to occur for an electrostatic field to interfere with a control circuit. Any objec
24、t that has pickedup a large electrostatic charge can create a voltage shift of several volts when brought in close proximity to acontrol circuit or cable. 4.1.2.16 Cable resonanceAvoiding unwanted resonances in signal and grounding cables from environmental EMI occurring at radiofrequencies has beco
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