ATIS 0600012-2011 Electrical Protection Considerations For Broadband Systems.pdf

1、 ATIS-0600012 ATIS Standard on - ELECTRICAL PROTECTION CONSIDERATIONS FOR BROADBAND SYSTEMS ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertainment and communications indust

2、ry. More than 200 companies actively formulate standards in ATIS Committees, covering issues including: IPTV, Cloud Services, Energy Efficiency, IP-Based and Wireless Technologies, Quality of Service, Billing and Operational Support, Emergency Services, Architectural Platforms and Emerging Networks.

3、 In addition, numerous Incubators, Focus and Exploratory Groups address evolving industry priorities including Smart Grid, Machine-to-Machine, Connected Vehicle, IP Downloadable Security, Policy Management and Network Optimization. ATIS is the North American Organizational Partner for the 3rd Genera

4、tion Partnership Project (3GPP), a member and major U.S. contributor to the International Telecommunication Union (ITU) Radio and Telecommunications Sectors, and a member of the Inter-American Telecommunication Commission (CITEL). ATIS is accredited by the American National Standards Institute (ANSI

5、). For more information, please visit . Notice of Disclaimer 350 mA heat coils have 4 of resistance. An alternative to heat coils is the Positive Temperature Coefficient (PTC) thermistor. From a current limiting standpoint, the resistance of the PTC increases as excessive currents heat the PTC, thus

6、 limiting the fault current. From a transmission standpoint, the PTC has minimal inductance, only resistance typically between 2 and 6 , thus not degrading the high frequency components of the broadband signal. The third type of current limiting device is the Electronic Current Limiter (ECL). The EC

7、L is a solid state device which switches very quickly from a low resistance state (typically 6 to 10 ) to an essentially open circuit when the designed current threshold is exceeded, thus opening the signal/surge path. When used, they are located on the equipment side of an overvoltage protection de

8、vice and keep the circuit open until the overvoltage protection device operates. When the overvoltage protection device operates, it shorts this surge current to ground. ECLs have a minimal amount of attenuation that is very uniform across all broadband spectrums. Note that a 6 device in each conduc

9、tor results in a total loop resistance increase of 12 that must be considered. ATIS-0600012 8 Table 1 : Primary Protector Voltage and Current Protection Comparisons Protection Element Surge Firing, Current Limiting Threshold Parente, M., IEEE Transactions on Power Delivery, Volume: 16, Issue: 1 Jan

10、2001 3. For a given fixed protector design approach, increasing surge capability increases capacitance. The use of a device with the minimum possible surge current capability results in the lowest capacitance possible. Device capacitance comparisons shall be made under the same measurement condition

11、s. A change in capacitance with voltage is often more important than absolute value. Absolute capacitance value alone may not completely guarantee the high frequency performance of a system. The capacitance change between 0 and -20 V is a more ATIS-0600012 15 important factor. The use of a series of

12、 low-capacitance diodes, three-phase diode bridges and series connected protectors (series or “Y” configurations) can further reduce system capacitance values. 7.4 Gas Tube + MOV: Backup or Hybrid Configuration The purpose of this section is to discuss the various types of gas tube + MOV protector c

13、omponents and their configuration. Careful selection of the gas tube and MOV is required to ensure the desired behavior. 7.4.1 Gas Tube + MOV: Backup The MOV can be used as a backup device which will fire only when the gas tube degrades to a high breakdown state. Figure 4: Gas Tube + MOV “Backup” Wi

14、th reference to Figure 4, the voltage on the line will increase across the GDT and MOV combination until the GDT sparkover voltage has been reached. At this point, the GDT gas will ionize and will cause the GDT to operate by switching into a virtual short circuit and shunt the surge current away fro

15、m the protected side which is often to ground. The MOV clamping voltage is high enough to ensure it does not normally conduct where the GDT will support all the fault current. The MOV provides back-up should the GDT let-through voltage become too high. 7.4.2 Gas Tube + MOV: Hybrid The MOV can be use

16、d in tandem, coordinating with the gas tube, to turn the protector on faster and lower the impulse breakdown voltage of the protector combination (hybrid) while allowing the gas tube part to take the brunt of the surge energy. Both operate on most surges. The clamping voltage of the MOV relative to

17、the breakdown voltage of the gas tube determines whether the combination is called a “backup” or a “hybrid”. ATIS-0600012 16 Figure 5: Gas Tube + MOV “Hybrid” With reference to Figure 5, the MOV has been designed to also be part of the active protection solution. The voltage on the line will increas

18、e across the GDT and MOV combination until the MOV starts to conduct. The conduction of the MOV has the effect of reducing the dv/dt of the fault voltage and therefore allows the GDT to operate at a lower voltage. There are two current paths where the first will be though the MOV until the sparkover

19、 voltage of the GDT is achieved. Once the GDT operates, all the fault current will be shunted through it. This combination normally provides a lower impulse sparkover voltage level compared to the solution shown in Figure 4. 8 SERVICE TO CELL TOWERS The wireless service provider industry typically h

20、ouses their equipment in a stand alone building, hut, or small enclosure co-located within the cellular tower site. A cellular customer may also be located in a multi-tenant building with the antenna or tower nearby. Such locations significantly increase the susceptibility of communications equipmen

21、t to the effects of lightning striking a tower - e.g., GPR from lightning and magnetic induction. Metallic facilities within such a location (as described in GR-1089-CORE Issue 6, type 3a/5a ports), as well those as serving such a location (as described in GR-1089-CORE Issue 6, type 3/5 ports), may

22、require electrical protection measures that exceed or differ from those defined in this ATIS Standard for less hazardous locations. Proper coordination of primary and secondary protectors can greatly improve service reliability. Providing communications service to cell towers with all dielectric fib

23、er significantly reduces the possibility of equipment damage. However, when providing service via fiber, care must be taken to adequately protect the power supply for any optical electrical conversion equipment. The DC power ports should, as a minimum, meet the requirements of GR-1089-CORE, Issue 6

24、34, Type 8a and 8b ports as applicable. Some locations in high lightning areas may require external surge arresters on the DC power ports of fiber optic equipment. Many wireless service providers place their equipment cabinets and antennas on power company high voltage (greater than 150 kV phase to

25、phase) transmission towers or on power company substation property. These locations are subject to high ground potential rises during power fault conditions. Communications circuits serving a high voltage transmission tower or substation require special high voltage protection. High voltage isolatio

26、n equipment shall be deployed at these locations as specified in IEEE 487, Recommended Practice for the Protection of Wire-Line Communication Facilities Serving Electric ATIS-0600012 17 Power Locations 5, and IEEE 1590, Recommended Practice for the Electrical Protection of Communication Facilities S

27、erving Electric Supply Locations Using Optical Fiber Systems 6. ATIS-0600012 18 Annex A (informative) A SUSCEPTIBILITY OF BROADBAND ARCHITECTURES TO VOLTAGE SURGES Telcordia Technical Reference TR-EOP-000001, Lightning, Radio Frequency, and 60-Hz Disturbances at the Bell Operating Company Network In

28、terface 13, provides some insight into the voltages to be expected at the Network Interface. Figure 1 in Section 6 demonstrates the dramatic difference in thunderstorm activity in various parts of the US. The Telcordia Technical Reference TR-EOP-000001 13 also contains distributions of the amplitude

29、 of surges. That data indicates that a surge having amplitude sufficient to operate a primary protector should be expected several times per thunderstorm day. Depending on the sample, this expectation is between about 5 and 30. Thunderstorms could result in surges on the Broadband Architectures and/

30、or they could result in disturbances on the AC mains. These induced surges are generally common-mode. These common-mode surges can be converted into differential mode via either longitudinal unbalance of the transmission facilities or by the asymmetric operation of protectors. The latter mechanism i

31、s more likely to result in higher voltages. An article in IEEE Transactions on Electromagnetic Compatibility, August 1996, titled “Statistical models for differential-mode conversion of common-mode impulse voltages measured on telecommunications pairs” 4, provides the results of some simulations tha

32、t project the frequency of asymmetric operation. That work suggests that such asymmetric operation could occur between 6 and 20 times per thunderstorm day. Malfunctioning equipment may also result in an AC power surge. ATIS-0600012 19 Annex B (informative) B RECOMMENDED READING 1 ANSI/IEEE 100-1996,

33、 Dictionary of electrical and electronics terms.52 ANSI/IEEE 776-1993 (R1998), Guide for inductive coordination of electrical supply and communication lines. 3 ANSI/NFPA 780-2008, Installation of lightning protection systems.64 ATIS-0600313.2008, Telecommunications - Electrical protection for teleco

34、mmunications central offices and similar type facilities.75 ATIS-0600316.2008, Telecommunications - Electrical protection of telecommunications outside plant.76 ATIS-0600332.2006, Electrical Protection of Broadband Facilities.77 ATIS-0600413.2009, Network and Customer Installation Interfaces Asymmet

35、ric Digital Subscriber Line (ADSL) Metallic Interface.78 ATIS-0600417.2007, Spectrum Management for Loop Transmission Systems.79 ATIS-0600418.2008, High bit rate Digital Subscriber Line-2ndGeneration (HDSL2/HDSL4) Issue 2.710 ATIS-0600424.2009, Interface between Networks and Customer Installation Ve

36、ry High Bit Rate Digital Subscriber Lines (VDSL) Metallic Interface (DMT based).711 IEEE 367, Recommended Practice for Determining the Electric Power Station Ground Potential Rise and Induced Voltage from a Power Fault.512 ETSI TS 101 524, Transmission and Multiplexing (TM); Access transmission syst

37、em on metallic access cables; Symmetrical single pair high bit rate Digital Subscriber Line (SDSL); Part 2: Transceiver requirements.813 European Standard 61000-4-5:1995, Electromagnetic Compatibility Part 4-5: Testing and measurement techniques S.914 ITU-T Recommendation G.991.1, High bit rate Digi

38、tal Subscriber Line (HDSL).1015 ITU-T Recommendation G.991.2, Single-pair high-speed digital subscriber line (SHDSL) transceivers.1016 ITU-T Recommendation G.992.1, Asymmetric digital subscriber line (ADSL) transceivers.1017 ITU-T Recommendation G.992.2, Splitterless asymmetric digital subscriber li

39、ne (ADSL) transceivers.105This document is available from the Institute of Electrical and Electronics Engineers (IEEE). 6This document is available from the National Fire Protection Association (NFPA). 7This document is available from the Alliance for Telecommunications Industry Solutions, 1200 G St

40、reet N.W., Suite 500, Washington, DC 20005. 8This document is available from the European Telecommunications Standards Institute (ETSI). 9This document is available from the International Electrotechnical Commission. 10This document is available from the International Telecommunications Union. ATIS-

41、0600012 20 18 ITU-T Recommendation G.992.3, Asymmetric digital subscriber line transceivers 2 (ADSL2).1019 ITU-T Recommendation G.992.4, Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2).1020 ITU-T Recommendation G.993.1, Very high speed digital subscriber line transceivers (VDSL).1021 ITU-T Recommendation G.993.2, Very high speed digital subscriber line transceivers 2 (VDSL2).1022 ITU-T Recommendation G.992.5, Asymmetric Digital Subscriber Line (ADSL)transceivers - Extended bandwidth ADSL2 (ADSL2+).10