1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T K.125 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2017) SERIES K: PROTECTION AGAINST INTERFERENCE Dangerous effects and protective measures against electromagnetic disturbances when an Internet data centre is co-sit
2、ed with a high-voltage substation Recommendation ITU-T K.125 Rec. ITU-T K.125 (07/2017) i Recommendation ITU-T K.125 Dangerous effects and protective measures against electromagnetic disturbances when an Internet data centre is co-sited with a high-voltage substation Summary Recommendation ITU-T K.1
3、25 specifies calculation methods for dangerous effects, tolerance limits of dangerous effects, tolerance limits of electromagnetic effects from a high-voltage substation, distance requirement and protection methods, protective measures, as well as requirements for the power frequency magnetic field
4、immunity of servers when an Internet data centre is co-sited with a high-voltage substation. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T K.125 2017-07-29 5 11.1002/1000/13279 Keywords Dangerous effect, electromagnetic disturbance, high-voltage substation, Internet data c
5、entre (IDC). * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T K.125 (07/2017) FOREWORD The International Telecommunication Uni
6、on (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions a
7、nd 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, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on th
8、ese 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 necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the exp
9、ression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applica
10、bility) 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 equivalents are used to express requirements. The use of such words does not suggest that compliance with the
11、 Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicabili
12、ty 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 had not received notice of intellectual property, protected by patents, which may be required to implement t
13、his 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.int/ITU-T/ipr/. ITU 2017 All rights reserved. No part of this publication may be reproduced, by any means wh
14、atsoever, without the prior written permission of ITU. Rec. ITU-T K.125 (07/2017) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 3 5 Conventions 3 6 Reference configuratio
15、n 3 7 Analysis on dangerous effect 4 7.1 Earthed type of high-voltage power system . 4 7.2 Calculation of dangerous effects 5 8 Synthesized tolerance limits of dangerous effects from high-voltage 5 8.1 General requirements 5 8.2 Synthesized tolerance limits . 5 9 Protective measures 6 9.1 IDC that i
16、s in close proximity, but not co-earthed with a high-voltage substation 6 9.2 IDC is co-earthed with high-voltage substation . 7 9.3 Methods for shortening the clearing time for earth fault 7 9.4 Step voltage and touch voltage . 7 10 Power frequency magnetic field and its mitigation measures 7 10.1
17、Characteristics of a power frequency magnetic field in a high-voltage substation 7 10.2 Power frequency magnetic field immunity requirements of servers in a cloud data centre . 8 10.3 Mitigation measures for the effect of power frequency magnetic field . 8 Appendix I Basic data for determining the t
18、olerance limits of dangerous effects on an IDC from a high-voltage system . 10 I.1 High-voltage transmission lines . 10 I.2 Earthed types of high-voltage transmission system . 10 I.3 Geographic environment between the high-voltage transmission lines and telecommunication network . 10 I.4 Parameters
19、of the communication network 11 Appendix II Limits related to danger in case of electromagnetic interference produced by AC power plants in fault conditions 12 Bibliography. 13 Rec. ITU-T K.125 (07/2017) 1 Recommendation ITU-T K.125 Dangerous effects and protective measures against electromagnetic d
20、isturbances when an Internet data centre is co-sited with a high-voltage substation 1 Scope This Recommendation specifies calculation methods for dangerous effects, tolerance limits of dangerous effects, tolerance limits of electromagnetic effects from a high-voltage substation, distance requirement
21、 and protection methods, protective measures, as well as requirements for power frequency magnetic field immunity of servers when an Internet data centre (IDC) is co-sited with a high-voltage substation. This Recommendation discusses co-sites for an IDC and a high-voltage substation while taking int
22、o account proximity, the co-earthing network, and shared accommodation. This Recommendation is applicable to IDCs and large communication centres co-sited with high-voltage substations. It is possible that this Recommendation may not apply to small Internet data sites. 2 References The following ITU
23、-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 references are subject to revision; users of this Recommendatio
24、n 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 to a document within this Recommendation does not give it,
25、 as a stand-alone document, the status of a Recommendation. ITU-T K.104 Recommendation ITU-T K.104 (2015), Method for identifying the transfer potential of the earth potential rise from high or medium voltage networks to the earthing system or neutral of low voltage networks. ITU-T K.107 Recommendat
26、ion ITU-T K.107 (2015), Method for determining the impedance to earth of earthing systems. IEC 61000-4-8 IEC 61000-4-8:2009, Electromagnetic compatibility (EMC) Part 4-8: Testing and measurement techniques Power frequency magnetic field immunity test. 3 Definitions 3.1 Terms defined elsewhere This R
27、ecommendation uses the following terms defined elsewhere: 3.1.1 common bonding network (CBN) b-ITU-T K.27: The CBN is the principal means for effecting bonding and earthing inside a telecommunication building. It is the set of metallic components that are intentionally or incidentally interconnected
28、 to form the principal bonding network (BN) in a building. These components include: structural steel or reinforcing rods, metallic plumbing, AC power conduit, protective conductors (PEs), cable racks and bonding conductors. The CBN always has a mesh topology and is connected to the earthing network
29、. 3.1.2 earthing network b-ITU-T K.27: The part of an earthing installation that is restricted to the earth electrodes and their interconnections. 2 Rec. ITU-T K.125 (07/2017) 3.1.3 (effective) touch voltage (195-05-11 of b-IEV): Voltage between conductive parts when touched simultaneously by a pers
30、on or an animal. NOTE The value of the effective touch voltage may be appreciably influenced by the impedance of the person or the animal in electric contact with these conductive parts. 3.1.4 grounded system b-IEEE Std. 142: A system in which at least one conductor or point (usually the middle wire
31、 or neutral point of transformer or generator windings) is intentionally grounded, either solidly or through an impedance. 3.1.5 high-resistance grounded b-IEEE Std. 142: A resistance-grounded system designed to limit ground-fault current to a value that can be allowed to flow for an extended period
32、 of time, while still meeting the criteria of R0 Xco, so that transient voltages from arcing ground faults are reduced. The ground-fault current is usually limited to less than 10 A, resulting in limited damage even during prolonged faults. NOTE R0 is the per-phase zero-sequence resistance of the sy
33、stem; Xco is the distributed per-phase capacitive reactance to ground of the system. 3.1.6 inductive coupling (131-12-33 of b-IEV): Coupling between electric circuit elements, by which an electric current in one of them gives rise to a linked flux between the terminals of another element. 3.1.7 low-
34、resistance grounded b-IEEE Std. 142: A resistance-grounded system that permits a higher ground-fault current to flow to obtain sufficient current for selective relay operation. Usually meets the criteria of R0/X0 less than or equal to 2. Ground-fault current is typically between 100 A and 1 000 A. N
35、OTE R0 is the per-phase zero-sequence resistance of the system; X0 is the zero-sequence reactance of the system. 3.1.8 resonant grounded b-IEEE Std. 142: A system in which the capacitive charging current is neutralized by an inductive current produced from a reactor connected between the system neut
36、ral and ground. By properly “tuning” the reactor (selecting the right tap), a low magnitude of fault current can be achieved. In general, when this occurs the arc will not maintain itself and the ground fault is extinguished or “quenched.” In a parallel circuit, consisting of L and C, this happens w
37、hen, = 1 or = 12 NOTE C is capacitance; f is frequency; L is inductance; is angular frequency. 3.1.9 solidly grounded b-IEEE Std. 142: Connected directly through an adequate ground connection in which no impedance has been intentionally inserted. NOTE Grounded is a synonym of earthed. The term earth
38、ed is used instead of grounded hereafter in this Recommendation for the sake of consistency. 3.1.10 step voltage (195-05-12 of b-IEV): Voltage between two points on the Earths surface that are 1 m distant from each other, which is considered to be the stride length of a person. 3.1.11 ungrounded sys
39、tem b-IEEE Std. 142: A system without an intentional connection to ground except through potential indicating or measuring devices or other very high-impedance devices. Rec. ITU-T K.125 (07/2017) 3 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 danger
40、ous effect: Effect on telecommunication line maintenance personnel and telecommunication equipment when power lines under normal operation or accident conditions induce nearby telecommunication lines and facilities to generate current and voltage due to the influences of inductive, capacitive and re
41、sistive couplings. 3.2.2 synthesized tolerance limits of dangerous effects from high-voltage: Vector sum of inductive coupling effect and resistive coupling effect on an Internet data centre from a high-voltage substation. 3.2.3 current-earthing coefficient: A ratio of the magnitude of current going
42、 back to earthed neutral point of the substation through earth return path from faulty short circuit point to the magnitude of total short circuit current going back to earthed neutral point of the substation transformer through earthing system and earth return path. 3.2.4 current-sharing coefficien
43、t: The value obtained by subtracting the current-earthing coefficient from 1. 3.2.5 transient co-earthed: The working earthing and shield earthing of an Internet data centre, as well as other earthing for lightning arrestors and surge protective devices, are divided into two independent earthing sys
44、tems that are connected together using a transient earthing protector; the two systems are unified if subject to lightning strike and work separately during normal operation. 3.2.6 high trustworthy power transmission lines: Power transmission lines of the neutral point directly earthed system, havin
45、g low failure rate, with short single phase earthing shorted fault current duration, typically less than 0.2 s, but not more than 0.5 s in most cases. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CRT Cathode Ray Tube EMF Electromotive Force EPR Eart
46、h Potential Rise ICT Information and Communication Technology IDC Internet Data Centre RMS Root Mean Square 5 Conventions None. 6 Reference configuration Where an IDC is co-sited with a high-voltage substation, basically two factors should be taken into consideration: the longitudinal electromotive
47、force (EMF) on the communication wires and cables that is induced from the transmission power system, and earth potential rise (EPR) of the earthing system in an IDC that is coupled through the earthing network. The vector sum of the two factors forms the dangerous effects on IDC, as shown in Figure
48、 1. 4 Rec. ITU-T K.125 (07/2017) Figure 1 - Reference structure of approach to synthesized dangerous effects on an Internet data centre from a high-voltage substation 7 Analysis on dangerous effect 7.1 Earthed type of high-voltage power system Power systems are classified into several types accordin
49、g to the earthing methods of their neutral point. The earthing method influences the rating and duration of fault current, thus influencing the magnitude of the EPR. For a power system having a solidly earthed or low-impedance earthed neutral point, the earth fault current is relatively high and the fault will be cleared by the relaying protection system in a short time. For a power system with a resonant earthed or high impedance earthed neutral point, the earth fault current is relatively low, typical
