ATIS 0600012 01-2017 Electrical Primary Protection Considerations for Broadband xDSL Systems.pdf

1、ATIS-0600012.01 ATIS Standard on Electrical Primary Protection Considerations for Broadband xDSL Systems Alliance for Telecommunications Industry Solutions Approved December 8, 2017 Abstract: xDSL Broadband equipment is susceptible to disturbances that require the use of electrical primary protectio

2、n devices. These primary protectors could have a negative impact on the signal of interest during steady-state conditions as well as during protector switching or clamping operation. The characteristics of these electrical primary protectors and their impact on xDSL broadband signals are considered

3、herein. This is the first communication service platform specific document in a suite of ATIS Standards intended to provide requirements and guidance for the use of electrical primary protectors in various technology architectures. This particular ATIS Standard will address xDSL. ATIS-0600012.01 ii

4、Foreword The Alliance for Telecommunication Industry Solutions (ATIS) serves the public through improved understanding between providers, customers, and manufacturers. The Sustainability in Telecom: Energy and Protection (STEP) Committee formerly the Network Interface, Power, and Protection Committe

5、e (NIPP) engages industry expertise to develop standards and technical reports for telecommunications equipment and environments in the areas of energy efficiency, environmental impacts, power and protection. The work products of STEP enable vendors, operators and their customers to deploy and opera

6、te reliable, environmentally sustainable, energy efficient communications technologies. STEP is committed to proactive engagement with national, regional and international standards development organizations and forums that share its scope of work. The mandatory requirements are designated by the wo

7、rd shall and recommendations by the word should. Where both a mandatory requirement and a recommendation are specified for the same criterion, the recommendation represents a goal currently identifiable as having distinct compatibility or performance advantages. The word may denotes a optional capab

8、ility that could augment the standard. The standard is fully functional without the incorporation of this optional capability. Suggestions for improvement of this document are welcome. They should be sent to the Alliance for Telecommunications Industry Solutions, STEP, 1200 G Street NW, Suite 500, W

9、ashington, DC 20005. At the time of consensus on this document, STEP, which was responsible for its development, had the following leadership: E. Gallo, STEP Chair and STEP NEP Vice Chair (Ericsson) J. Fuller, STEP Vice Chair and STEP NEP Chair (AT Access transmission system on metallic access cable

10、s; Symmetrical single pair high bit rate Digital Subscriber Line (SDSL); Part 2: Transceiver requirements.9 106 ITU-T Recommendation G.991.1, High bit rate digital subscriber line (HDSL).10 107 ITU-T Recommendation G.991.2, Single-pair high-speed digital subscriber line (SHDSL) transceivers.10108 IT

11、U-T Recommendation G.992.1, Asymmetric digital subscriber line (ADSL) transceivers.10109 ITU-T Recommendation G.992.2, Splitterless asymmetric digital subscriber line (ADSL) transceivers.10110 ITU-T Recommendation G.992.3, Asymmetric digital subscriber line transceivers 2 (ADSL2).10111 ITU-T Recomme

12、ndation G.992.4, Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2).10112 ITU-T Recommendation G.992.5, Asymmetric digital subscriber line (ADSL) transceivers - Extended bandwidth ADSL2 (ADSL2+).10113 ITU-T Recommendation G.993.1, Very high speed digital subscriber l

13、ine transceivers (VDSL).10114 ITU-T Recommendation G.993.2, Very high speed digital subscriber line transceivers 2 (VDSL2).10115 ITU-T Recommendation G.993.5, Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers.103 Definitions, Acronyms, it will conduct current once its breakdown volt

14、age has been exceeded (it is a variable resistor model). 3.1.18 Positive Temperature Coefficient (PTC) thermistor: A current limiting device, the resistance of which increases as a function of the temperature caused by the heating effect of the current and PTC resistance. 3.1.19 Primary Protector: U

15、sed to protect an equipment interface and wiring system located where it diverts most of the stressful voltages and currents from propagation into the equipment thus protecting inside wiring. It also minimizes voltage gradients within outside plant wiring but does not limit current in outside plant

16、wiring. It is generally accessible, removable, and connected to equipotential bonding. 3.1.20 Quiescent State (Off-State): The surge protector, while not being exposed to external voltages that would cause it to operate, should present low loss at transmission frequencies. ATIS-0600012.01 5 3.1.21 T

17、hyristor: A semi-conductor device that conducts current by switching into a short-circuit once its breakdown voltage has been exceeded. The thyristor is reset back into its high-impedance state once the current falls below its holding current value. 3.1.22 Transverse Voltage (also known as Different

18、ial or Metallic Voltage): A voltage between the tip conductors and the ring conductors. 3.2 Acronyms Access transmission system on metallic access cables; Symmetrical single-pair high bit rate Digital Subscriber Line (SHDSL); Part 2: Transceiver requirements 105. ATIS-0600012.01 7 SHDSL is typically

19、 used as a transport technology to commercial customer locations due to its high-speed symmetric characteristics. SHDSL can be used by applications that require symmetric access. The international standard for SHDSL is ITU-T Recommendation G.991.2, Single-pair high-speed digital subscriber line (SHD

20、SL) transceivers 107. The highest signal frequencies for SHDSL are: 385kb/s 120 kHz; 784 kb/s 250 kHz; 1.56 Mb/s 500 kHz. ADSLx can transmit a high speed down-stream data rate up to 27 Mbps to the subscriber, a lower speed up-stream data rate up to 2 Mbps, and can coexist with Plain Old Telephone Se

21、rvice (POTS). When POTS and ADSLx coexist on the same twisted-pair, then a splitter/filter is required at the Network End (Central Office, Remote Terminal, etc.) and at the Remote End (Customer Location) to separate the POTS and ADSLx signals. The ADSLx technology is intended for applications such a

22、s internet access, multimedia access, and video on demand that can be provided by an asymmetric system. The standard for ADSL is ATIS-0600413, Network and Customer Installation Interfaces Asymmetric Digital Subscriber Line (ADSL) Metallic Interface 101. The international standards for ADSL are the I

23、TU-T standards ITU-T Recommendation G.992.1, Asymmetric digital subscriber line (ADSL) transceivers 108 and ITU-T Recommendation G.992.2, Splitterless asymmetric digital subscriber line (ADSL) transceivers 109. The ADSL2 standards are ITU-T Recommendation G.992.3, Asymmetric digital subscriber line

24、transceivers 2 (ADSL2) 110 and ITU-T Recommendation G.992.4, Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2) 111. The ADSL2plus standard is ATIS-0600417, Spectrum Management for Loop Transmissions Systems 102. The international standard is ITU-T Recommendation G.9

25、92.5, Asymmetric digital subscriber line (ADSL) transceivers - Extended bandwidth ADSL2 (ADSL2+) 112. The highest signal frequency for ADSL and ADSL2 is 1.1 MHz. VDSLx is similar to ADSLx access but at higher data rates on shorter loop distances than ADSLx and can be symmetric or asymmetric. The VDS

26、L standard is ATIS-0600424, Interface between Networks and Customer Installation Very High Bit Rate Digital Subscriber Lines (VDSL) Metallic Interface (DMT based) 104. The international standard for VDSL is ITU-T Recommendation G.993.1, Very high speed digital subscriber line transceivers (VDSL) 113

27、 and for VDSL2 it is ITU-T Recommendation G.993.2, Very high speed digital subscriber line transceivers 2 (VDSL2) 114. The highest signal frequency for VDSL1 and VDSL2 is up to 30 MHz (some versions stop at 8.5 or 17 MHz.) Table 4.1 - DSL Systems Technology Data Rate Mode Some Applications ISDN (Int

28、egrated Services Digital Network) 144 kbps (2B+D) Duplex Voice and Data Communication HDSL,2,4 (High-Speed Digital Subscriber Line) 1.544 Mbps (T1) 2.048 Mbps (E1/J1) Duplex Duplex T1/E1/J1 Service, Feeder Plant, WAN and LAN access, internet server access SDSL (Symmmetric Digital Subscriber Line) Up

29、 to 2.048 Mbps (E1/J1) Duplex E1/J1 Service, Feeder Plant, WAN and LAN access, internet server access SHDSL (Symmetric High-Speed Digital Subscriber Line) Up to 5.7 Mbps Duplex Same as HDSL, plus location access for symmetric services ADSL (Asymmetric Digital Subscriber Line) Up to 9 Mbps Up to 640

30、kbps Downstream upstream Internet access, video on demand, remote LAN access, interactive media ADSL2 (Asymmetric Digital Subscriber Line) Up to 12 Mbps Up to 2Mbps Downstream upstream Internet access, video on demand, remote LAN access, interactive media ADSL2plus (Asymmetric Digital Subscriber Lin

31、e) Up to 27 Mbps Up to 2Mbps Downstream upstream Internet access, video on demand, remote LAN access, interactive media ATIS-0600012.01 8 Technology Data Rate Mode Some Applications VDSL (Very High Data Rate Digital Subscriber Line) Up to 52 Mbps Up to 7 Mbps Downstream Upstream Same as ADSL and Hig

32、h Definition TV VDSL2 (Very High Data Rate Digital Subscriber Line) Up to 100 Mbps Up to 100 Mbps Downstream Upstream Same as ADSL and High Definition TV The transport capacity of the DSL systems depend on the physical characteristics of the twisted-pair cabling system such as cable length, wire gau

33、ge, impairments (example: cross talk, impulse noise, etc), and the presence of bridge taps and load coils. The transmission rate is constrained by the line attenuation that increases as the line length, wire gauge, and frequency increase. Figures 4.1, 4.2, 4.3, and 5.1 demonstrate the typical differ

34、ences in loop lengths at which each technology is capable of operating. 4.1 Pair Bonding (Non-Physical Layer Bonding) The use of more than one ADSL2plus or VDSL2 line typically two lines for residential service, and up to twelve lines for a business customer to provide service to a customer is refer

35、red to as pair bonding and enables much higher bit rates or service to longer lines. For a given loop length, bonding two lines approximately doubles both the downstream and upstream service bit-rates. Alternatively, for the same bit-rate, bonding two lines enables approximately 50% longer lines tha

36、n using one line. Bonding, in combination with vectoring, could make 100 Mb/s up to 500m (1.64 kft) on 24 AWG and 40 Mbps to 1220m (4 kft) on 24 AWG service cost-effective for many more customers. 4.2 Performance Comparisons of Different xDSL Technologies The various technologies of xDSL have very d

37、ifferent performance characteristic. Within each technology type, there are performance differences, i.e., synchronization rate or data rate, based on loop length as shown in Figures 4.1, 4.2, 4.3, and 5.1 below. Figure 4.1 is based on data from Broadband Forum (BBF) TR100 Table A.1-15; Figure 4.2 i

38、s based on data from BBF TR114 Table 46; and Figure 4.3 is based on data from BBF TR114 Table 62. ATIS-0600012.01 9 Figure 4.1 - Rate and Reach Performance - ADSL2plus Figure 4.2 - Rate and Reach Performance - VDSL2 profile 8d ATIS-0600012.01 10 Figure 4.3 - Rate and Reach Performance - VDSL2 profil

39、e 17a 5 Available Primary Protection Technologies The following types of primary surge protection devices are commonly used in the telecommunications network: Carbon Air Gap; Gas Tube; Gas Tube with Back-Up Air Gap (BUG); Gas Tube with Metal Oxide Varistor (MOV) Backup: Hybrid - Gas Tube with MOV; a

40、nd Solid State. Performance testing of protection devices is described in Telcordia GR-974-CORE, Generic Requirements for Telecommunications Line Protector Units 12, and in Telcordia GR-3154-CORE, Generic Requirements for High-Density Feeder Distribution Interconnection and Surge Protection 13. The

41、impulse breakdown voltage characteristic of these devices is illustrated in Figure 5.2 below. The breakdown voltage distribution comparison is shown in Figure 5.1 below. ATIS-0600012.01 11 Figure 5.1 - Breakdown Voltage Comparisons Figure 5 Figure 5.2 - Impulse Breakdown, Gas Tube, Hybrid, Solid Sta

42、te 5.1 Carbon Air Gap Protectors These devices consist of two small carbon electrodes which provide a small (3 to 6 mils) air gap between a conductor and ground. During a surge event, if the potential difference between the conductors and ground across the carbon electrodes exceeds the sparkover rat

43、ing of the gap, an arc will be established, grounding the line 100 V/us Impulse Breakdown Voltage(New Protectors / Full -20 to +65C Temperature Range)3104152903805451060020040060080010001200Carbon Gas Tube Solid StateBreakdown Voltage(Volts)Breakdown Voltage Distribution ComparisonBreakdown Voltage(

44、Volts)TimeVoltageGas TubeHybrid (Gas + MOV)Solid StateImpulse Breakdown VoltageVoltage100 V/s Impulse Breakdown Voltage (New Protectors / Full -20 to +65 C Temperature Range) ATIS-0600012.01 12 conductor. If the surge is short-lived (e.g., a lightning stroke), the arc-over will be extinguished when

45、the current in the conductor is reduced to below approximately 50 mA, allowing the protector to return to its open-circuited condition. During steady-state discharges of considerable duration (e.g., power cross), the air gap is permanently shorted, grounding the conductor and providing a low impedan

46、ce path to ground. When the fault on the conductor is cleared, the carbon block protector must be replaced. Carbon air gap protectors are not recommended for use with modern xDSL technologies. These items may be difficult to acquire or replace. They may produce distortion or noise performance relate

47、d issues with xDSL equipment. 5.2 Gas Tube Protectors Gas Discharge devices are switching overvoltage protectors that have a discontinuous voltage/current (VI) characteristic. Power loss occurs in the glow and arc regions of the Gas Discharge Tubes (GDT) characteristic. By changing the formulation o

48、f the gas in a GDT, “regular” and “fast” devices can be fabricated. Fast GDTs offer lower impulse sparkover (at the expense of a shorter life for high surges wearout), but higher glow and arc voltage values. Typically, the arc voltage of a fast GDT is about two to three times higher than a regular G

49、DT arc voltage. Capacitance of the GDT is normally linear and only a few pF, and as a result has little or no effect on broadband signals regardless of the frequency. Figure 5.3 - Gas Tube Operating Regions When the voltage across the GDT conductors reaches its sparkover value, the GDT will enter into its glow voltage region. The sparkover voltage is dependent on the rate of voltage rise (dv/dt) across its conductors. A GDT DC sparkover is characterized with a ramp rate of 100-300 V/s and addresses low frequency fault events s