1、 International Telecommunication Union ITU-T K.28TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2012) SERIES K: PROTECTION AGAINST INTERFERENCE Parameters of thyristor-based surge protective devices for the protection of telecommunication installations Recommendation ITU-T K.28 Rec. ITU-T K.28
2、(05/2012) i Recommendation ITU-T K.28 Parameters of thyristor-based surge protective devices for the protection of telecommunication installations Summary Recommendation ITU-T K.28 defines the parameters, test circuits and performance values of thyristor-based surge protective devices (SPDs) used fo
3、r the protection of telecommunication installations (for example, exchange equipment, access equipment, telecommunication lines and subscriber or customer equipment). This Recommendation should be used for the harmonization of existing or future specifications issued by thyristor-based SPD manufactu
4、rers, telecommunication equipment manufacturers, administrations or network operators. History Edition Recommendation Approval Study Group 1.0 ITU-T K.28 1991-03-18 V 2.0 ITU-T K.28 1993-03-12 V 3.0 ITU-T K.28 2012-05-29 5 Keywords In-line SPD, leakage resistance, overvoltage protector, surge protec
5、tive device, SPD, thyristor. ii Rec. ITU-T K.28 (05/2012) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T)
6、is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years
7、, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necess
8、ary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However,
9、 the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equ
10、ivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a
11、claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU h
12、ad not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.i
13、nt/ITU-T/ipr/. ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T K.28 (05/2012) iii Table of Contents Page 1 Scope 1 2 References. 2 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms def
14、ined in this Recommendation . 3 4 Abbreviations and acronyms 4 5 Conventions 4 6 Electrical parameters 5 6.1 Overvoltage function characteristics 5 6.2 Series element characteristics . 7 6.3 Signal characteristics 9 6.4 Ratings 10 6.5 Overload parameters . 12 7 Test methods . 13 7.1 Characteristics
15、13 7.2 Series element characteristics . 16 7.3 Signal characteristics 18 7.4 Rating tests . 19 7.5 Overload parameters . 20 8 Identification . 21 8.1 Marking 21 8.2 Documentation . 21 9 Ordering information 21 Annex A Impulse generators . 22 A.1 Introduction 22 A.2 Waveform tolerances 22 A.3 1.2/50
16、8/20 impulse generator . 23 A.4 10/700 impulse generator . 23 A.5 10/1000 impulse generator . 23 A.6 8/20 current impulse generator . 23 Bibliography. 24 iv Rec. ITU-T K.28 (05/2012) Introduction Thyristor overvoltage protectors are often likened to the solid-state equivalent of gaseous discharge ov
17、ervoltage protectors like the gas discharge tube (GDT) b-ITU-T K.12. While the general protection principles of thyristors and GDTs are similar, the test circuits for parametric measurement are often not the same due to technology differences. Thyristors require significant current to transition fro
18、m a voltage limiting condition into low-voltage conduction and have a lower inherent surge current capability. Thyristor overvoltage protectors are used in environments where the surge levels are known and a well-defined voltage limiting level is needed. Rec. ITU-T K.28 (05/2012) 1 Recommendation IT
19、U-T K.28 Parameters of thyristor-based surge protective devices for the protection of telecommunication installations 1 Scope This Recommendation applies to thyristor-based surge protective devices (SPDs) to be used for primary protection against surges due to lightning or power disturbances on tele
20、communication circuits, in accordance with b-ITU-T K.11. It covers the following device parameters: a) Characteristics 1. Overvoltage function i. Impulse limiting voltage ii. Leakage current and insulation resistance iii. Holding current 2. Series element i. Hold current ii. Trip current iii. Time-t
21、o-trip iv. Impulse let-through current 3. Signal i. Capacitance ii. Longitudinal conversion loss (LCL) iii. Insertion loss iv. Return loss b) Ratings 1. Rated peak impulse current 2. Impulse durability 3. AC durability c) Overload parameters 1. High impulse current 2. Power fault d) Identification a
22、nd marking. This Recommendation does not deal with: a) mountings for SPDs and their effect on arrester characteristics; b) hybrid SPDs where the thyristor voltage limiting is augmented by other technologies; c) mechanical dimensions; d) quality assurance requirements; e) units containing heat-coils.
23、 2 Rec. ITU-T K.28 (05/2012) 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other refe
24、rences are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference
25、 to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T K.20 Recommendation ITU-T K.20 (2011), Resistibility of telecommunication equipment installed in a telecommunications centre to overvoltages and overcurrents. ITU-T K.21 Recom
26、mendation ITU-T K.21 (2011), Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents. ITU-T K.45 Recommendation ITU-T K.45 (2011), Resistibility of telecommunication equipment installed in the access and trunk networks to overvoltages and overcurr
27、ents. ITU-T K.82 Recommendation ITU-T K.82 (2010), Characteristics and ratings of solid-state, self-restoring overcurrent protectors for the protection of telecommunications installations. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1
28、 electronic current limiter (ECL) ITU-T K.82: A device based on transistor and related technology that automatically restricts the current amplitude when it exceeds a predetermined threshold level. 3.1.2 fault current, Ifault b-IEC 62319-1: Current used when measuring time-to-trip. 3.1.3 hold curren
29、t (self-restoring overcurrent limiter), IHITU-T K.82: Maximum current at specified ambient temperature, which will not cause the trip event. NOTE Sometimes known as rated or non-tripping current. 3.1.4 holding current (thyristor overvoltage limiter), Ihb-IEC 61643-341: Minimum anode, principal, or t
30、hyristor current that maintains the thyristor in the on-state. NOTE The holding current test is the thyristor equivalent of the holdover test of a gas discharge tube. 3.1.5 impulse generator charge voltage, VC ITU-T K.82: Value of impulse generator charging voltage. 3.1.6 insertion loss (of a two-po
31、rt device) b-IEV 702-07-08: The ratio, generally expressed in decibels, of the apparent power at a point in a transmission channel to the power at the same point after insertion of a given two-port device into the transmission channel immediately ahead of this point. NOTE If the ratio defining the i
32、nsertion loss is less than one, its decibel value is negative, and its converse or opposite decibel value called “insertion gain“ may be used. 3.1.7 longitudinal conversion loss (LCL) b-CISPR 16-1-2: In a one- or two-port network, a measure (a ratio expressed in dB) of the degree of unwanted transve
33、rse (symmetric mode) signal produced at the terminals of the network due to the presence of a longitudinal (asymmetric mode) signal on the connecting leads. Rec. ITU-T K.28 (05/2012) 3 3.1.8 port b-IEV 131-12-60: Access to a device or network where electromagnetic energy or signals may be supplied o
34、r received or where the device or network variables may be observed or measured. NOTE An example of a port is a terminal pair. 3.1.9 reflection loss factor b-IEV 131-12-65: Ratio of the apparent power that a specified source would deliver to a load with zero reflection factor at its interface with t
35、he source, to the apparent power delivered by the same source to a directly connected given load. 3.1.10 return loss b-IEV 702-07-25: The modulus of the reciprocal of the reflection factor, generally expressed in decibels. NOTE When impedances can be defined, the return loss is given by the formula:
36、 ()()20)lg(20ZZZZr+= where Z is the characteristic impedance of a transmission line ahead of a discontinuity, or the impedance of a source, and Z is the impedance after the discontinuity or the load impedance seen from the junction between the source and the load. 3.1.11 surge protective device (SPD
37、) b-ITU-T K.72: Device that restricts the voltage of a designated port or ports, caused by a surge, when it exceeds a predetermined level. NOTE 1 Secondary functions may be incorporated, such as a current-limiting device to restrict a terminal current. NOTE 2 Typically, the protective circuit has at
38、 least one non-linear voltage-limiting surge protective component. NOTE 3 An SPD is a combination of a protection circuit and holder. 3.1.12 time-to-trip (PTC thermistor) ttripITU-T K.82: Under specified ambient conditions, starting from the time the fault current (Ifault) is applied, the time-to-tr
39、ip is the time required for a device to transition into a tripped state. NOTE An overcurrent protector shall have passed into the tripped condition as indicated by the measured voltage exceeding 90% of the supply open-circuit voltage. 3.1.13 trip current (self-restoring overcurrent limiter), It ITU-
40、T K.82: Lowest current which will cause a trip event at a specified temperature and within a time specified in the product specification. 3.1.14 trip event (self-restoring overcurrent limiter) ITU-T K.82: Event of rapid increasing resistance in response to an overcurrent surge. 3.1.15 two-port b-IEV
41、 131-12-65: Device or network with two separate ports. 3.1.16 user agreed values ITU-T K.82: Test parameters and circuits agreed between major stakeholders (e.g., user and manufacturer) for a specific application. 3.2 Terms defined in this Recommendation This Recommendation defines the following ter
42、ms: 3.2.1 impulse limiting voltage, VP: Highest value of voltage across the terminals of the SPD during the application of a specified impulse. NOTE Also called voltage protection level or measured limiting voltage. 3.2.2 in-line SPD: A two-port SPD connected in series with the service feed. 3.2.3 i
43、nsulation resistance (effective): Quotient of the voltage applied to a designated terminal pair, VIR, by the current, IIR, drawn from the applied voltage. 4 Rec. ITU-T K.28 (05/2012) 3.2.4 let-through current: In-line SPD peak short-circuit output current when a specified impulse is applied to the S
44、PD input. 3.2.5 rated peak impulse current: Maximum value of peak impulse current of specified amplitude and waveshape that may be applied without causing degradation. 3.2.6 semiconductor arrester assembly (SAA): A surge protective device (SPD) that uses thyristor technology as the main overvoltage
45、limiting element. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AC Alternating Current ADSL Asymmetric Digital Subscriber Line CMI Common Mode Injector DC Direct Current DSL Digital Subscriber Line ECL Electronic Current Limiter GDT Gas Discharge Tub
46、e LBB Longitudinal Balanced Bridge LCL Longitudinal Conversion Loss POTS Plain Old Telephone Service PTC Positive Temperature Coefficient PVC Polyvinyl Chloride SAA Semiconductor Arrester Assembly SPD Surge Protective Device VDSL Very high speed Digital Subscriber Line 5 Conventions The original ver
47、sion of ITU-T K.28 b-ITU-T K.28 mainly used material from the United States of America standards available at that time. The definition of a semiconductor arrester assembly (SAA) was intended to denote a surge protective device (SPD) that used thyristor technology as the main overvoltage limiting el
48、ement. Unfortunately, the term “semiconductor“ covers a large range of voltage limiting components other than just a thyristor component. For this reason this version of ITU-T K.28 uses thyristor-based SPD (or simply SPD for brevity) rather than SAA. For the protection of twisted pair cables an SPD
49、can be connected in shunt (Figure 1-a) or in-line (Figure 1-b) with the cable. Shunt SPDs can be tested in the in-line SPD test circuits by shorting the corresponding port input and output terminals together. In-line SPDs can incorporate series overcurrent protectors, either temperature or current operated (Figure 1-c). Additional tests are required to measure the overcurrent protection element operation, surge withstand and surge current let through. Rec. ITU-T K.28 (05/2012) 5 Figure 1 SPD confi
