IEEE Std 1590-2009 IEEE Recommended Practice for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Using Optical Fiber Systems.pdf
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1、IEEE Std 1590-2009 (Revision of IEEE Std 1590-2003) IEEE Recommended Practice for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Using Optical Fiber Systems IEEE 3 Park Avenue New York, NY 10016-5997, USA 26 June 2009 IEEE Power +1 978 750 8400. Permission to
2、 photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center. Authorized licensed use limited to: Tsinghua University Library. Downloaded on December 25,2010 at 10:49:34 UTC from IEEE Xplore. Restrictions apply. Introduction
3、 This introduction is not part of IEEE Std 1590-2009, IEEE Recommended Practice for the Electrical Protection of Communication Facilities Serving Electric Supply Locations Using Optical Fiber Systems. Some electrical environments, collectively called electric supply locations, require the applicatio
4、n of unique electrical protection techniques because of their special nature. One such environment is the electric power station or substation. Another is at, or near, power line transmission and distribution structures such as towers or poles. Such structures often provide a convenient site for the
5、 location of wireless, personal communications service, and cellular antennas and their associated electronic equipment that is served by a link to the wired telecommunications network. IEEE Std 487-2007a provides additional details on these locations. This recommended practice assumes that optical
6、fiber cables are to be used to provide electrical isolation for telecommunications services to these electric supply locations. Refer to IEEE Std 367-1996 or IEEE Std 487-2007. This recommended practice describes applications consisting entirely of fiber and applications where both metallic cables a
7、nd fiber cables are used. In the latter case, i.e., hybrid applications, the user is referred to IEEE Std 487-2007 for the metallic portion of the application. Some delays in site activation often occur due to the time involved in obtaining electrical information data for most high-voltage tower or
8、pole sites. The delays may be eliminated by using the fiber optical solutions described in this recommended practice. This recommended practice has been prepared by the Wireline Working Group of the Power System Communications Committee of the IEEE Power this overhead grounding system will reduce gr
9、ound return current at individual towers and reduce clearing time of the fault by providing a more direct path to operate relays. These systems follow many different protection designs, from being grounded at each tower and the substations to being insulated with a 3 to 5 kV spark gap device at ever
10、y tower or every fourth tower. They may be stopped two to four spans before the substation or extend from the substation three to four spans only to protect the substation alone. In low lightning areas, they may not exist at all, and each tower is left to stand on its own. The net effect of the over
11、head grounding system is to reduce the ground return current at individual towers by providing multiple discharge paths. This, in turn, reduces the current flowing through the ground grid reduces clearing time, and lowers fault-produced GPR to manageable levels. Typical grounding requirements for BT
12、S Several documents, such as R56B B32, are in general use in the wireless industry. These documents provide minimum grounding requirements, along with site preparation recommendations, necessary to meet personnel safety and warranty conditions from the equipment vendors or manufacturers. These docum
13、ents tend to recommend low ground impedances for 50 to 60 Hz power as well as lightning frequencies at the sites. When the sites are located at, or near, power line transmission and distribution structures such as towers or poles, enhancements of the ground field may be necessary to meet these requi
14、rements to reduce step, touch, and mesh voltages. As a reminder, and for the purposes of this recommended practice, mesh voltage is the maximum touch voltage to be found within a mesh of a ground grid; step voltage is the difference in surface potential experienced by a person bridging a distance of
15、 1 m (3 ft) with his or her feet without contacting any other grounded object; and touch voltage is the potential difference between the GPR and the surface potential at the point where a person is standing, while at the same time having his or her hands in contact with a grounded structure.13 13 Ta
16、ken from IEEE Std 80-2000. 16 Copyright 2009 IEEE. All rights reserved. Authorized licensed use limited to: Tsinghua University Library. Downloaded on December 25,2010 at 10:49:34 UTC from IEEE Xplore. Restrictions apply. IEEE Std 1590-2009 IEEE Recommended Practice for the Electrical Protection of
17、Communication Facilities Serving Electric Supply Locations Using Optical Fiber Systems 8.6.4 Step, touch, and mesh voltages for BTSs located on power line transmission or distribution structures Lightning and 50 to 60 Hz fault currents for BTSs located on a high-voltage transmission structures can f
18、low on three predominant conducting paths back to their source(s) within the power grid. The first path is the tower sky wire system (when used) grounded to earth and near tower groundings in, on, or adjacent to the lines right of way (ROW). The second path is the tower and BTS combined grounding sy
19、stem. The third path is through the local power system ground that provides power to the site. Figure 5 depicts these current distribution paths (see Grcev et al. B11 and B13). AC POWER BTS RADIO SKY WIRES LIGHTNING STRIKE NOTEReprinted with permission from Grcev et al. B11. Figure 5 Possible lightn
20、ing current distributions for a BTS on a power tower The distribution, or current magnitude on the various paths, becomes a function of the path impedance at the various fault frequencies. The frequency and fault current path relationships are shown in Figure 6. According to Grcev et al. B11, B12, a
21、nd B13, at the fundamental 50 to 60 Hz power frequencies the sky wires conduct approximately 60% of the fault current while the tower/BTS grounding system conducts less that 10% to remote earth (low-frequency GPR). The remaining current follows the local ac power grounding network and distributes it
22、 throughout the community (see Rajotte et al. B33). At lightning frequencies approaching 10 to 100 kHz, the inductive characteristic of the sky wires and local power present higher impedances, while the tower presents a lower impedance to ground and conducts over 90% of lightning fault currents (hig
23、h-frequency GPR). 17 Copyright 2009 IEEE. All rights reserved. Authorized licensed use limited to: Tsinghua University Library. Downloaded on December 25,2010 at 10:49:34 UTC from IEEE Xplore. Restrictions apply. IEEE Std 1590-2009 IEEE Recommended Practice for the Electrical Protection of Communica
24、tion Facilities Serving Electric Supply Locations Using Optical Fiber Systems MAGNITUDE OF CURRENT (%) FREQUENCY (Hz) 100 100 80 60 40 20 0 1k10k100k1e+6 SKY WIRES TOWER GROUNDS LV-MV POWER 50-60Hz NOTEReprinted with permission from Grcev et al. B12. Figure 6 Current distribution between sky wires,
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