1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0600338.2016 Electrical Coordination of Primary and Secondary Surge Protection for Use in Telecommunications Circuits As a leading technology and solutions development organization, the Alliance for Telecommunications Industry Solutions (ATIS)
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11、rican National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer the primary PPS device or component is a switching type and the secondary PSS protector component is a switching type . 9 ATIS-0600338.2016
12、v Figure 6.3 Coordination of primary and secondary protection; the primary protector PPS is a switching device or component, and the secondary protector PSC is a clamping component 10 Figure 6.4 Conditions to activate primary and secondary protection; the primary protector PPC is a clamping device o
13、r component, and the secondary protector PSS is a switching component 11 Figure 6.5 Conditions to activate primary and secondary protection; both the primary protector device or component (PPC) and the secondary protector component (PSC) are clamping types 12 Figure 6.6 Graph for calculating the val
14、ue of the coordinating impedance, Z, knowing the activation threshold of the primary protector, VPS or VPC, as a percent of the source voltage VS . 13 Figure A.1 Coordination of primary and secondary protection, both the primary PPS and secondary PSS protectors are switching components . 17 Figure A
15、.2 Coordination of primary and secondary protection, when the primary protector PPS is a switching component and the secondary protector PSC is a clamping component . 18 Figure A.3 Coordination of primary and secondary protection, when the primary protector PPC is a clamping component and the second
16、ary protector PSS is a switching component . 19 Figure A.4 Coordination of primary and secondary protection, when both the primary protector PPC and the secondary protector PSC are clamping components 20 Figure C.1 Longitudinal equipment testing 24 Figure C.2 Transverse (metallic) equipment testing
17、24 Figure C.3 Longitudinal coordination testing 25 Figure C.4 Transverse (metallic) coordination testing . 26 Figure C.5 Longitudinal equipment testing 26 Figure C.6 Transverse (metallic) equipment testing 27 Figure C.7 Longitudinal coordination testing 27 Figure C.8 Transverse (metallic) coordinati
18、on testing . 27 Figure C.9 Network V-I lightning levels 28 Figure C.10 Equivalent lightning source impedances 29 Figure C.11 Generator based on peak voltage (2 kV) and peak current (50 A) 29 Figure C.12 Thevenin and Norton generators based on line impedance (200 ), peak current (50 A) and insulation
19、 breakdown (2 kV) 30 Figure C.13 System I-V conditions for different generators . 30 Figure C.14 Error in coordination generator approach 31 Figure D.1 Primary protector PP and secondary protector PS, separated by impedance, Z. 32 Figure D.2 Common cable types . 33 Figure D.3 Modes of protection 34
20、Figure D.4 Delta and Star configuration limiting voltage equivalence 34 Figure D.5 Parallel GDT-MOV hybrid 35 Figure D.6 Cascaded primary protection example . 36 Figure D.7 3-electrode and 2-electrode GDT operation . 37 Figure D.8 Star protector circuit, characteristic and operation . 37 Figure D.9
21、Bridged Thyristor Protector 38 Figure D.10 Coordination by current-triggered thyristor . 39 Figure D.11 VI Characteristics of an ECL 40 Figure D.12 Primary protector and modem 41 Figure D.13 Primary Protector and SLIC . 41 Figure D.14 Primary protector and DSL circuit 42 Figure D.15 Primary protecto
22、r and ECL protected DSL circuit 43 Figure E.1 Double-exponentiel impulse . 44 Figure E.2 Single-exponential impulse 45 Figure E.3 Component V-I characteristic . 50 ATIS-0600338.2016 vi Table of Tables Table 6.1 Minimum values of coordination impedances 13 Table 7.1 Surge generators used for coordina
23、tion . 14 Table B.1 Minimum coordination impedance comparisons . 22 Table B.2 Minimum coordination impedance requirements . 23 Table C.1 ITU-T equipment tests . 25 Table C.2 ITU-T coordination tests 25 AMERICAN NATIONAL STANDARD ATIS-0600338.2016 American National Standard for Telecommunications Ele
24、ctrical Coordination of Primary and Secondary Surge Protection for Use in Telecommunications Circuits 1 1 Scope This document covers the electrical coordination between primary and secondary surge protection devices or components for a single conductor line that may have an earth ground connection r
25、eference. Additional information covering coordination, such as dual conductors connected that may have an earth ground connection reference, is included in the annexes. Proper coordination is essential to ensure that both primary and secondary protectors function in a manner that provides the prote
26、cted equipment with the most effective protection from ac power fault conditions or lightning induced or industrial equipment induced surges. This document does not address protection of the ac power service. 2 Normative References The following standards contain provisions which, through reference
27、in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying t
28、he most recent editions of the standards indicated below. NFPA 70-2014, National Electrical Code.13 Terms, Letter Symbols, Definitions, and a secondary Surge Protective Component (SPC) normally located within the protected equipment, or Surge Protective Device (SPD) normally located externally to th
29、e protected equipment. When properly coordinated with secondary protectors and attached equipment, a primary protector is used to prevent excessive currents and voltages from entering a structure, internal wiring, or equipment, where they could cause injury or damage. Primary protectors often trade
30、off an ability to handle large voltages and currents against an activation threshold, which can be substantially higher than the operating voltages and currents of the network. Because the voltages and currents passed by the primary protector may be large enough to damage the telecommunications equi
31、pment connected to the public switched telephone network (PSTN), secondary SPCs may be used to reduce these voltages and currents to a level as close as possible to the operating voltages and currents of the protected equipment. If the surge exceeds the rated limits of the SPC, the result is general
32、ly a short circuit failure mode of the SPC, which protects the equipment but does remove it from operational status. Primary and secondary protection is typically accomplished by diverting an overstress either to ground or around the equipment protected. Figure 4.1 illustrates this concept. 4.2 Type
33、s of Coordination Figure 4.1 gives an overview of how coordination may be achieved, and shows the presence of a coordinating element between the primary and secondary protector. The coordination element is typically an impedance. The value of this impedance may depend on both frequency and current m
34、agnitude of the steady-state signals and/or the surge or power fault event, and may also be time-dependent. ATIS-0600338.2016 4 4.2.1 System Coordination From a system standpoint, the requirement is that no failures occur, up to the maximum specified surge level. The primary protector may or may not
35、 operate. If the primary protector does not operate, then the equipment, coordinating element (current limiting component if installed), and the secondary protector shall be robust enough to withstand the surge without additional protection. If the secondary protector is not sufficiently rated for t
36、he expected surge levels without the primary protector activating, the coordinating element must limit the current to protect the SPC. Otherwise, the primary protector does need to operate, and either voltage-type or current-type coordination needs to be considered. 4.2.2 Voltage-type Coordination I
37、n this case, the primary protector has the lowest threshold of activation of any of the shunt elements in the system, so only the primary operates. Since the other protection elements do not operate, it is not necessary to consider these elements further. The threshold of activation of the primary p
38、rotector shall be low enough that the equipment voltage withstand is not exceeded. 4.2.3 Current-type Coordination In this case, several protection elements operate. It is now necessary to consider how the current flow through the coordination element and following circuitry develops sufficient volt
39、age to operate the primary protector. This case is considered in detail in Clauses 5 and 6. If the voltage developed across the coordinating element and following circuitry is not sufficient to operate the primary protector, the secondary protector and the coordination element needs to support this
40、voltage and current or they could be damaged. Figure 4.1 Coordination Overview NOTES: 1. VPis the primary protector operating voltage, VSC is the secondary protector operating voltage or equipment withstand. CoordinationPrimary Protector Operates?NOYESSystem CoordinationPRIMARYCoordination ElementSE
41、CONDARYVP VSVoltage-type CoordinationPRIMARYCoordination ElementSECONDARYCurrent-type CoordinationPRIMARYCoordination ElementSECONDARYYESNOATIS-0600338.2016 5 2. No failures shall occur for surge levels up to the maximum specified level. 3. Voltage-type and system coordination designs do not require
42、 a discrete coordination element or component. 4. Current-type coordination designs using fixed voltage primary protectors require a coordination element. 5. Voltage- and current-triggered primary protectors (see GR-974-CORE fast current limiters) are a special case; these automatically give current
43、-type coordination above the current trigger threshold and may not require a coordination element. 6. Failures below the maximum specified level are the result of blind spots in the design. 7. Blind spots cannot occur in voltage-type coordination designs. 8. For switching-type primary protectors and
44、 current-type coordination designs, potential blind spots occur at the surge level just before the primary begins to switch and the following circuit elements have the maximum stress of an un-truncated surge waveshape. 9. In some cases, a coordination element will be present as the result of other f
45、unctional requirements, such as series resistance from PTC thermistors used for ac fault current limiting and from line feed resistors used for stabilizing POTS SLIC ICs. Due to hysteresis and possible resistance changes due to repeated operation, the balance of a circuit using PTCs may adversely af
46、fect high speed circuit such as xDSL. 10. Coordination is assisted by the PCB or wire trace inductance, resistance, and propagation delay characteristics. In some cases, these characteristics alone may form the needed coordination function. 5 Coordination Elements the magnetic core saturation will e
47、ffectively remove the transformer action. A parameter for core saturation is ampere-seconds, the product of applied winding current and time for saturation to occur. Such chokes will only provide effective coordination to common-mode surges up to the time that the ampere-second rating is not exceede
48、d. Transverse or single conductor surges can cause complex reactions and the following points need to be considered: 1. The effective series inductance in the surged conductor will be the choke leakage inductance. 2. Transformer action, up to the winding volt-second rating, may cause secondary prote
49、ctor conduction to ground in the opposite surge polarity on the un-surged conductor. ATIS-0600338.2016 8 3. Transformer action, up to the winding volt-second rating, may cause any inter-conductor secondary protection to conduct current and prevent conduction of any secondary protector conduction to ground on the surged conductor. 5.7 Cable Time Delay Coordination The connection cable between the primary and secondary protection is often thought to provide coordin
