ATIS 0600332-2015 Electrical Protection of Network-Powered Broadband Facilities.pdf

1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0600332.2015 Electrical Protection of Network-Powered Broadband Facilities As a leading technology and solutions development organization, the Alliance for Telecommunications Industry Solutions (ATIS) brings together the top global ICT companie

2、s to advance the industrys most pressing business priorities. ATIS nearly 200 member companies are currently working to address the All-IP transition, network functions virtualization, big data analytics, cloud services, device solutions, emergency services, M2M, cyber security, network evolution, q

3、uality of service, billing support, operations, and much more. These priorities follow a fast-track development lifecycle from design and innovation through standards, specifications, requirements, business use cases, software toolkits, open source solutions, and interoperability testing. ATIS is ac

4、credited by the American National Standards Institute (ANSI). The organization is the North American Organizational Partner for the 3rd Generation Partnership Project (3GPP), a founding Partner of the oneM2M global initiative, a member of and major U.S. contributor to the International Telecommunica

5、tion Union (ITU), as well as a member of the Inter-American Telecommunication Commission (CITEL). For more information, visit www.atis.org. AMERICAN NATIONAL STANDARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteri

6、a for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not n

7、ecessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made towards their resolution. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the sta

8、ndards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover,

9、 no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAU

10、TION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current in

11、formation on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer however, it is not transparent to any broadband signals that may be present. 3.4 Electronic equipment enclosure (EEE): An electronic equipment enclosure (EEE) is an enclosure housing tele

12、communications equipment. It may consist of a weatherproof enclosure, equipment pod, or an equipment hut. The EEE may be located remotely from a central office or a headend. The EEE may be located above or below ground. The temperature and humidity within the EEE may be controlled. The EEE is served

13、 by telecommunications outside plant facilities, which may be aerial, directly buried, or placed in underground conduit. It may also be served by commercial ac power facilities, and may have provisions for standby power. 3.5 Hard line (equipment): The coaxial distribution cables are referred to as h

14、ard line owing to their construction, which utilizes solid metal sheath design. 3.6 Indoor Unit (IDU): In broadband wireless system the equipment, receiving or transmitting or both, associated with premises distribution system that are located indoors; i.e., not exposed directly to weather. 3.7 Inte

15、r Facility Link (IFL): In wireless installations, the entire segment of the bundled drop cable (outdoor and indoor) between the ODU and the IDU. A typical installation may involve one or more coaxial cables, multiple twisted pair cable, and possibly a fiber optic cable. An IFL may carry low or high

16、power RF broadband signal, control signals, and DC or AC current used to power the serving terminal equipment (ODU). 3.8 Network-powered broadband communications circuit: (per ANSI/NFPA 70, Article 830): The circuit extending from the communications utilitys serving terminal or tap up to and includi

17、ng the NIU. NOTE - A typical single-family network-powered communications circuit consists of a communications drop or communications service cable and an NIU and includes the communications utilitys serving terminal or tap where it is not under the exclusive control of the communications utility. 3

18、.9 Network Interface Unit (NIU) (per ANSI/NFPA 70, Article 830): A device that converts a broadband signal into component voice, audio, video, data, and interactive services signals. The NIU provides isolation between the network power and the premises signal circuits. The NIU may also contain prima

19、ry and secondary protectors. 3.10 Outdoor Unit (ODU): In broadband wireless system, the serving terminal equipment (receiving or transmitting or both) located in the proximity of the antenna. In very small installations this term may refer to the entire antenna-equipment assembly. 3.11 Plastic (Poly

20、olefin) Insulated Conductor (PIC): Solid copper conductors insulated with polyolefin or plastic material that are used in twistedpair cables. 3.12 Reference Point 0 (RP 0): The point at which all ground categories within the facility shall be referenced to earth. Reference Point 0 is identical to th

21、e Building Principal Ground (BPG) of ATIS-0600333. 3.13 Tap: The multiport serving terminal device installed on the hard line distribution cable providing interface between the coaxial service drop cable and the broadband telecommunications plant distribution network. 4 Exposure 4.1 Sources of Expos

22、ure Broadband facilities might be exposed to unwanted voltages and currents resulting from any of the following: Disturbances from lightning; Contact with electric power circuits; ATIS-0600332.2015 4 Ground potential rise; Induction from electric power lines; or Resistive coupling in coaxial distrib

23、ution systems. 4.1.1 Lightning Disturbances Lightning can create disturbances to the broadband facilities by either a direct strike to a broadband facility or by a strike near the facility. Some of the lightnings electromagnetic energy could also be coupled to the power wires or to the cables carryi

24、ng telecommunications or broadband signals. The level of exposure should be determined from the Risk Assessment Guide contained in Appendix L of ANSI/NFPA 780. Outside plant cables, either aerial or buried, may be subject to effects of lightning. A buried broadband cable or wire can become a conduct

25、or of lightning currents resulting from nearby strokes to the earth. A determination of the exposure status of broadband facilities shall take into account both the exposure of the structure itself (e.g., central office, headend, or EEE), as well as the outside plant cables that serve them. 4.1.2 Co

26、ntact with Power Circuits Power, broadband, and telecommunications companies (utilities) often serve the same customers and frequently employ joint-use outside plant facilities such as poles or common trenches. Clearances and separations for joint-use facilities are regulated by either ANSI C2 (NESC

27、) or local codes. Power contact may result from a falling phase conductor into aerial plant or during excavations in buried plant areas. 4.1.3 Ground Potential Rise (GPR) During normal conditions, the power systems grounded neutral conductor is generally at the same potential as remote earth. GPR oc

28、curs during a power fault when the fault current returns to its source through the earth. During fault conditions, the potential at the local ground of the broadband facilities rises with respect to remote earth. 4.1.4 Power Induction Power and telecommunications (broadband) outside plant facilities

29、 frequently occupy joint structures or a common right-of-way, and as such occupy parallel routes. The proximity of broadband metallic cables to power lines can result in voltages being induced on the broadband metallic facilities by either magnetic or electric fields. 4.1.4.1 Magnetic Field Inductio

30、n The varying magnetic fields produced by currents in a nearby power line may result in large voltages being induced into the broadband outside plant facility through inductive coupling, especially under certain conditions on the power facility such as a phase-to-neutral fault. 4.1.4.2 Electric fiel

31、d induction Ungrounded broadband outside plant cables, hardware, and personnel located in the vicinity of extra high voltage (EHV) power transmission lines (greater than 300 kV phase-to-phase) may become electrically energized by electrostatic coupling to the EHV power lines. An ungrounded object in

32、cluding a person will assume a potential ATIS-0600332.2015 5 relative to the earth, based upon the voltage and geometry of the power line and the capacitance of the object, or person, with respect to both the power line and the earth. The induced voltages can be quite large and the available current

33、 is usually quite small (below the level that might cause electrical injury). However, the resulting electric shock or arc may be startling, causing accidental injury as a result of an involuntary reaction. Grounding (earthing) of broadband cables and hardware helps to minimize the possibility for i

34、njury, resulting from such involuntary reactions, by keeping the cables and hardware and the earth near them at the same potential. 4.1.5 Resistive Coupling Coaxial cable distribution systems in joint use with commercial ac power systems are subject to resistive coupling. Resistive coupling occurs w

35、hen the coaxial cable shield, which is bonded to the neutral of the power distribution system for safety, provides an alternate path for the power distribution system neutral current. The current of the power distribution system present in the coaxial cable shield, because of the shield resistance,

36、will cause center conductor-to-shield voltages to be coupled into the coaxial cable. The magnitude of these voltages is dependent upon the shield current and the mutual impedance between the coaxial cable shield and center conductor. Resistively coupled voltages, under power fault conditions, can be

37、 sufficiently high as to require electrical protection. 4.2 Classification of Exposure A determination of the exposure status of a broadband facility shall take into account both the exposure of the structure itself (e.g., central office, headend, or EEE), as well as the outside plant cables that se

38、rve it. Any facility that is classified as exposed shall require coordinated electrical protection. Underground construction methods, by design, help to eliminate the possibility of power contacts. Cables in conduit on bridges and underpasses are treated the same as underground cables. Cables mounte

39、d on bridge supports are treated as aerial cable. Submarine cable is regarded as buried cable. 4.2.1 Exposure to Lightning A broadband facility shall be classified as exposed to lightning unless it is located in an area having an average of five (5) or fewer thunderstorm-days per year and earth resi

40、stivity of less than 100 ohm-meters as measured in accordance with IEEE 81. Structures or cables that are located at elevations significantly above the average elevation of the surrounding terrain such as hill-tops, fire towers, and airport control towers, are considered exposed to lightning regardl

41、ess of thunderstorm incidence and earth resistivity. Broadband facilities should be classified as unexposed to lightning when located in a geographic area treated as unexposed by the serving utility. This area may be a metropolitan location (also called a block) having a high density of multi-story

42、buildings and an extensive network of buried metallic piping systems and cables. In these areas, lightning-induced surges are unlikely to enter the facility through the serving cables, which are effectively shielded and grounded (earthed). Although the facility itself may not be within the zone of p

43、rotection of a higher structure, the risk of damage from a direct lightning stroke is considered a low probability event. 4.2.1.1 Structures A structure or building shall be classified as exposed if the broadband outside plant serving it, or the commercial ac power serving it, is exposed to lightnin

44、g. Each structure intended to house a switching or transmission system should be evaluated to determine the need for a lightning protection system (LPS). The decision on whether or not to provide an LPS should be based on the Risk Assessment Guide contained in Appendix L of ANSI/NFPA 780. ATIS-06003

45、32.2015 6 4.2.1.2 Central Office, Remote Site, The broadband network plant is exposed to possible power contact or induction in excess of 300 volts rms to ground; The building or structure containing broadband facilities is exposed to possible ground potential rise in excess of 300 volts rms with re

46、spect to remote earth. Where paired-conductor and coaxial cables are exposed to power contact greater than 300 volts rms to ground, a fuse link shall be applied to limit power currents to a value that can be safely carried by the listed primary protector. There shall be no exposure to power contact

47、between the fuse link location and the terminus of the broadband network plant. Both the voltage-limiting and current-limiting functions may be incorporated in the listed primary protector. Isolation techniques may also be used in areas where stray dc currents contribute to electrolysis (corrosion).

48、 The broadband network plant may be paired-conductor, optical fiber, or coaxial cable, or a composite cable containing any combination of these, together with amplifiers, power-passing taps, and NIU to distribute the broadband services to customers. 5.1.1 National Electrical Code Considerations Arti

49、cle 830 of ANSI/NFPA 70 (NEC) covers the installation of broadband facilities at customers structures or buildings, extending from the power-passing tap to the NIU. However, Article 830 does not explicitly address the customer powered serving terminals (such as antenna mounted radio equipment) used for delivery of broadband services (see 8.2.1.1). Article 840 of the NEC covers networks that are powered from the customer premises ATIS-0600332.2015 8 Article 810 of ANSI/NFPA 70 covers the installation of the Radio and Television Equipment. Sections 810.15 and 810.21