1、 International Telecommunication Union ITU-T K.12TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2010) SERIES K: PROTECTION AGAINST INTERFERENCE Characteristics of gas discharge tubes for the protection of telecommunications installations Recommendation ITU-T K.12 Rec. ITU-T K.12 (05/2010) i Rec
2、ommendation ITU-T K.12 Characteristics of gas discharge tubes for the protection of telecommunications installations Summary Recommendation ITU-T K.12 defines the basic characteristics to be met by gas discharge tubes for the protection of exchange and outdoor equipment, subscriber or customer equip
3、ment and telecommunication lines from surges. It is intended to be used for the harmonization of existing or future specifications issued by gas discharge tube manufacturers, telecommunication equipment manufacturers, administrations or network operators. History Edition Recommendation Approval Stud
4、y Group 1.0 ITU-T K.12 1976-10-08 2.0 ITU-T K.12 1980-11-21 3.0 ITU-T K.12 1981-07-21 V 4.0 ITU-T K.12 1984-10-19 5.0 ITU-T K.12 1988-11-25 6.0 ITU-T K.12 1995-05-31 5 7.0 ITU-T K.12 2000-02-25 5 8.0 ITU-T K.12 2006-02-13 5 9.0 ITU-T K.12 2010-05-29 5 Keywords Electrical characteristics and test met
5、hods, gas discharge tube (GDT). ii Rec. ITU-T K.12 (05/2010) 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-
6、T) 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 ye
7、ars, 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 nec
8、essary 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. Howev
9、er, 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
10、equivalents 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
11、 a 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, IT
12、U had 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.it
13、u.int/ITU-T/ipr/. ITU 2010 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.12 (05/2010) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations 3 5 Storage conditions 3 6 Electr
14、ical requirements . 3 6.1 Spark-over voltages (see clause 7.1) 4 6.2 Insulation resistance (see clause 7.2) 6 6.3 Capacitance . 6 6.4 Transverse voltage 6 6.5 d.c. holdover voltages (see clauses 7.5 and Figures 4 and 5) . 6 6.6 Life tests (see clause 7.6) 7 6.7 Short-circuit behaviour . 8 7 Test met
15、hods . 8 7.1 Spark-over voltage 8 7.2 Insulation resistance . 9 7.3 Capacitance . 9 7.4 Impulse transverse voltage for 3-electrode gas discharge tubes 9 7.5 Holdover test 10 7.6 Life tests . 11 7.7 Short-circuit test . 13 8 Environment tests . 13 8.1 Radiation . 13 8.2 Robustness of terminations . 1
16、3 8.3 Solderability . 13 8.4 Resistance to soldering heat . 13 8.5 Vibration . 14 8.6 Damp heat cyclic 14 8.7 Sealing 14 8.8 Low temperature . 14 9 Informative characteristics 14 10 Identification . 15 10.1 Marking 15 10.2 Documentation . 15 11 Ordering information 15 iv Rec. ITU-T K.12 (05/2010) Pa
17、ge Annex A Test circuit for GDT used in ISDN circuits. 16 Annex B Spark-over test waveform 17 Annex C Determining the special test protector (STP). 18 Bibliography. 20 Rec. ITU-T K.12 (05/2010) 1 Recommendation ITU-T K.12 Characteristics of gas discharge tubes for the protection of telecommunication
18、s installations 1 Scope This Recommendation: a) gives the characteristics of gas discharge tubes used in accordance with b-ITU-T K.11 and b-ITU-T K.46 for the protection of exchange and outdoor equipment, subscriber or customer equipment and telecommunication lines against overvoltages; b) deals wit
19、h gas discharge tubes having two or three electrodes; c) does not deal with mountings and their effect on tube characteristics (see ITU-T K.65); characteristics apply to gas discharge tubes as a component, mounted only in the ways described for the tests; d) does not deal with mechanical dimensions;
20、 e) does not deal with quality assurance requirements; f) does not deal with gas discharge tubes which are connected to electrical power systems. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of t
21、his Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references 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 oth
22、er references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T K.65 Recommendation ITU-T K.65 (2004), Overvoltage and ove
23、rcurrent requirements for termination modules with contacts for test ports or SPDs. IEC 60060 IEC 60060-1 and IEC 60060-2 (1989/1994), High voltage test techniques Part 1: General definitions and test requirements and Part 2: Measuring systems. IEC 60068-2-1 IEC 60068-2-1 (2007), Environmental testi
24、ng Part 2-1: Tests Test A: Cold. IEC 60068-2-6 IEC 60068-2-6 (2007), Environmental testing Part 2-6: Tests Test Fc: Vibration (sinusoidal). IEC 60068-2-17 IEC 60068-2-17 (1994), Basic environmental testing procedures Part 2-17: Tests Test Q: Sealing. IEC 60068-2-20 IEC 60068-2-20 (2008), Environment
25、al testing Part 2-20: Test Test T: Test methods for solderability and resistance to soldering heat of devices with leads. IEC 60068-2-21 IEC 60068-2-21 (2006), Environmental testing Part 2-21: Tests Test U: Robustness of terminations and integral mounting devices. IEC 60068-2-30 IEC 60068-2-30 (2005
26、), Environmental testing Part 2-30: Tests Test Db: Damp heat, cyclic (12 h + 12 h cycle). 2 Rec. ITU-T K.12 (05/2010) IEC 61643-21 IEC 61643-21 (2000), Low voltage surge protective devices Part 21: Surge protective devices connected to telecommunications and signalling networks Performance requireme
27、nts and testing methods. 3 Definitions This Recommendation defines the following terms: 3.1 arc mode: The lowest impedance or on-state of a gas discharge tube during normal operation (Figure 6). 3.2 arc voltage: The voltage measured across the tube while in lowest impedance state or arc mode (Figure
28、 6). 3.3 breakdown: See “spark-over“. 3.4 current turn-off time: The time required for the gas discharge tube to return itself to a non-conducting state following a period of conduction. 3.5 d.c. holdover voltage: The maximum d.c. voltage across the terminals of a gas discharge tube under which it m
29、ay be expected to clear and to return to the high impedance state after the passage of a surge, under specified circuit conditions. 3.6 destruction characteristic: The relationship between the value of the discharge current and the time of flow until the gas discharge tube is mechanically destroyed
30、(break, electrode short-circuit). For periods of time between 1 s and some ms, it is based on impulse discharge currents, and for periods of time of 0.1 s and greater, it is based on alternating discharge currents. 3.7 discharge current: The current that passes through a gas discharge tube when spar
31、k-over occurs. discharge current, alternating: The r.m.s. value of an approximately sinusoidal alternating current passing through the gas discharge tube. discharge current, impulse: The peak value of the impulse current passing through the gas discharge tube. 3.8 discharge voltage: The voltage that
32、 appears across the terminals of a gas discharge tube during the passage of discharge current. 3.9 gas discharge tube: A gap, or several gaps, in an enclosed discharge medium, other than air at atmospheric pressure, designed to protect apparatus or personnel, or both, from high transient voltages; s
33、ee clause 9 for the electrical characteristics of GDT also referred to as “gas tube surge arrester“. 3.10 glow mode: This is a semi on-state in the area of the V/I curve where only a limited glow-current flows and the device has not yet turned on or reached the lowest impedance arc-mode (Figure 6).
34、3.11 glow current: The current which flows after spark-over when circuit impedance limits the discharge current to a value less than the glow-to-arc transition current. 3.12 glow voltage: The peak value of the voltage drop across the GDT when a glow current is flowing. It is sometimes called the glo
35、w-mode voltage (Figure 6). 3.13 glow-to-arc (transition) current: The current required for the gas discharge tube to pass from the glow-mode into the arc mode. 3.14 impulse waveshape: An impulse waveform designated as x/y has a rise time of x s and a decay time to half value of y s as standardized i
36、n IEC 60060. Rec. ITU-T K.12 (05/2010) 3 3.15 nominal alternating discharge current: For currents with a frequency of 15 Hz to 62 Hz, the alternating discharge current which the gas discharge tube is designed to carry for a defined time. 3.16 nominal d.c. spark-over voltage: The voltage specified by
37、 the manufacturer to designate the gas discharge tube (type designation) and to indicate its application with respect to the service conditions of the installation to be protected. Tolerance limits of the d.c. spark-over voltage are also referred to the nominal d.c. spark-over voltage. 3.17 nominal
38、impulse discharge current: The peak value of the impulse current with a defined wave-shape with respect to time for which the gas discharge tube is rated. 3.18 residual voltage: See “discharge voltage“. 3.19 spark-over: An electrical breakdown of the discharge gap of a gas discharge tube. Also refer
39、red to as “breakdown“. 3.20 spark-over voltage: The voltage which causes spark-over when applied across the terminals of a gas discharge tube (Figure 6). spark-over voltage, d.c.: The voltage at which the gas discharge tube sparks over when a slowly rising d.c. voltage up to 2 kV/s is applied. spark
40、-over voltage, impulse: The highest voltage which appears across the terminals of a gas discharge tube in the period between the application of an impulse of given wave-shape and the time when current begins to flow. 3.21 transverse voltage: For a gas discharge tube with several gaps, the difference
41、 of the discharge voltages of the gaps assigned to the two conductors of a telecommunications circuit during the passage of discharge current. 4 Abbreviations This Recommendation uses the following abbreviations: GDT Gas Discharge Tube ISDN Integrated Services Digital Network xDSL Digital Subscriber
42、 Line 5 Storage conditions Gas discharge tubes shall be capable of withstanding the following conditions without damage: Temperature: 40 to +70C; Relative humidity: up to 95%. See also clauses 8.6 and 8.8 for environmental conditions. 6 Electrical requirements Gas discharge tubes should have the fol
43、lowing characteristics when tested in accordance with clause 7. Clauses 6.1 to 6.5 apply to virgin gas discharge tubes and also, where quoted in clause 6.6, to tubes subjected to life tests. NOTE Using GDTs in circuits protecting certain systems can cause secondary effects like oscillations. This be
44、haviour is dependent on certain circuit combinations like impedance and inductance in connection with certain GDT parameters like glow-to-arc transition current, etc. This phenomenon has not been studied adequately at this time and will be added to future work of ITU-T. 4 Rec. ITU-T K.12 (05/2010) 6
45、.1 Spark-over voltages (see clause 7.1) Spark-over voltages between the electrodes of a 2-electrode tube or between either line electrode and the earth electrode of a 3-electrode tube shall be within the limits in either Table 1a or 1b. NOTE 1 For the definition of spark-over waveforms, see Annex B.
46、 Two types of GDT may be differentiated by their voltage nominal values. By employing special design techniques on either types, the disadvantages of the different technologies, to a certain extent, could be compensated for. The values for these types are given in Tables 1a and 1b. Type 1 (Table 1a)
47、 represents the common type with a technology well suited for high current protection accomplished by a low glow voltage and arc voltage. Type 2 (Table 1b) represents the low impulse spark-over voltage type which has a faster response time, thus achieving lower impulse spark-over voltages with highe
48、r glow voltage and arc voltage, but offer lower current carrying capabilities. For 3-electrode tubes, the spark-over voltage between the line electrodes shall not be less than the minimum d.c. spark-over voltages in either Table 1a or 1b. It is recommended to achieve at least 1.2 times the minimum d
49、.c. spark-over voltage given in either Table 1a or 1b. NOTE 2 For 3-electrode GDTs, the maximum d.c. spark-over voltage a-b (line-line) may be restricted; a reasonable value is about 1.8-2.0 times the voltage a/b-c. 6.1.1 Spark-over voltage values for type 1 GDT (common type) This type represents a technology well suited for high current protection accomplished by a low glow-voltage and arc-voltage (Table 1a). Table 1a Spark-over voltage values for common types of GDT Spark-over volta
