1、BRITISH STANDARD BS EN 61472:2004 Live working Minimum approach distances for a.c. systems in the voltage range 72,5 kV to 800 kV A method of calculation The European Standard EN 61472:2004 has the status of a British Standard ICS 13.260; 29.240.20; 29.260.99 BS EN 61472:2004 This British Standard w
2、as published under the authority of the Standards Policy and Strategy Committee on 20 January 2005 BSI 20 January 2005 ISBN 0 580 45277 8 National foreword This British Standard is the official English language version of EN 61472:2004. It is identical with IEC 61472:2004. The UK participation in it
3、s preparation was entrusted to Technical Committee PEL/78, Tools for live working, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publ
4、ications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the ne
5、cessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the in
6、terpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 42, an inside back cover and
7、a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD EN 61472 NORME EUROPENNE EUROPISCHE NORM November 2004 CENELEC European Committee for Electrotechnical Standardiz
8、ation Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61472:2004 E IC
9、S 13.260; 29.240.20; 29.260.99 English version Live working Minimum approach distances for a.c. systems in the voltage range 72,5 kV to 800 kV A method of calculation (IEC 61472:2004) Travaux sous tension Distances minimales dapproche pour des rseaux courant alternatif de tension comprise entre 72,5
10、 kV et 800 kV Une mthode de calcul (CEI 61472:2004) Arbeiten unter Spannung Mindest-Arbeitsabstnde fr Wechselspannungsnetze im Spannungsbereich von 72,5 kV bis 800 kV Berechnungsverfahren (IEC 61472:2004) This European Standard was approved by CENELEC on 2004-10-01. CENELEC members are bound to comp
11、ly with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Sec
12、retariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as
13、 the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovaki
14、a, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 67412:2400 - - 2 Foreword The text of document 78/582/FDIS, future edition 2 of IEC 61472, prepared by IEC TC 78, Live working, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61472 on 2004-10-01. This st
15、andard has been prepared according to the requirements of EN 61477: Live working Minimum requirements for the utilization of tools,devices and equipement, where applicable. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identi
16、cal national standard or by endorsement (dop) 2005-07-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2007-10-01 _ Endorsement notice The text of the International Standard IEC 61472:2004 was approved by CENELEC as a European Standard without any mod
17、ification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: IEC 60060-1 NOTE Harmonized as HD 588.1 S1:1991 (not modified). IEC 60071-1 NOTE Harmonized as EN 60071-1:1995 (not modified). IEC 60071-2 NOTE Harmonized as EN 60071-2:1997 (not m
18、odified). IEC 60743 NOTE Harmonized as EN 60743:2001 (not modified). IEC 61477 NOTE Harmonized as EN 61477:2002 (not modified). _ Page2 EN61472:200467412 IE2:C 400 3 CONTENTS 1 Scope.5 2 Terms, definitions and symbols 5 3 Methodology.8 4 Factors influencing calculations9 5 Evaluation of risks13 6 Ca
19、lculation of minimum approach distance D A 14 Annex A (informative) Ergonomic distance.18 Annex B (informative) Overvoltages.20 Annex C (informative) Dielectric strength of air 24 Annex D (informative) Gap factor k g .26 Annex E (informative) Allowing for atmospheric conditions 28 Annex F (informati
20、ve) Influence of electrically floating objects on the dielectric strength 32 Annex G (informative) Live working near contaminated, damaged or moist insulation 39 Bibliography42 Figure 1 Illustration of two floating objects of different dimensions and at different distances from the axis of the gap (
21、see 4.3.4).16 Figure 2 Typical live working tasks (see Clause 2 and 4.3.4) .17 Figure B.1 Ranges of u e2at the open ended line due to closing and reclosing according to the type of network (meshed or antenna) with and without closing resistors and shunt reactors (see B.2.1.1).23 Figure F.1 Reduction
22、 in the discharge voltage of the air gap due to alteration in the electric field caused by the presence of a floating-potential conductive object in critical position along the axis of the gap (phase to earth rod-rod configuration) 250 s /2 500 s impulse (see F.3.1.2 et F.3.1.3) .36 Figure F.2 Reduc
23、tion in the discharge voltage of the air gap due to alteration in the electric field caused by the presence of a floating-potential conductive object in critical position along the axis of the gap (phase to phase conductor-conductor configuration) 250 s /2 500 s impulse (see F.3.1.2 et F.3.1.3) 37 F
24、igure F.3 Reduction of the dielectric strength as a function of the clearance D for constant values of Phase to earth rod-rod configuration (see F.3.1.3 and F.3.2) .38 Figure F.4 Reduction of the dielectric strength as a function of the clearance D for constant values of Phase to phase conductor-con
25、ductor configuration (see F.3.1.3 and F.3.2).38 Page3 EN61472:200467412 IE2:C 400 4 Table 1 Floating object factor k f .12 Table 2 Example of calculation of electrical distance for some switching overvoltage values.15 Table B.1 Classification of overvoltages according to IEC 60071-1 22 Table D.1 Gap
26、 factors for some actual phase to earth configurations.27 Table E.1 Atmospheric factor k afor different reference altitudes and values of U 90 30 Table G.1 Example of maximum number of damaged insulators calculation (gap factor 1,4).40 Table G.2 Example of maximum number of damaged insulators calcul
27、ation (gap factor 1,2).41 Page4 EN61472:200467412 IE2:C 400 5 LIVE WORKING MINIMUM APPROACH DISTANCES FOR AC SYSTEMS IN THE VOLTAGE RANGE 72,5 kV TO 800 kV A METHOD OF CALCULATION 1 Scope This International Standard describes a method for calculating the minimum approach distances for live working,
28、at maximum voltages between 72,5 kV and 800 kV. This standard addresses system overvoltages, and the working air distances between parts and/or workers at different potentials. The required withstand voltage and minimum approach distances calculated by the method described in this standard are evalu
29、ated taking into consideration the following: workers are trained for, and skilled in, working in the live working zone; the anticipated overvoltages do not exceed the value selected for the determination of the required minimum approach distance; transient overvoltages are the determining overvolta
30、ges; tool insulation has no continuous film of moisture present on the surface; no lightning is seen or heard within 10 km of the work site; allowance is made for the effect of conducting components of tools; the effect of altitude on the electric strength is taken into consideration. For conditions
31、 other than the above, the evaluation of the minimum approach distances may require specific data, derived by other calculation or obtained from additional laboratory investigations on the actual situation. 2 Terms, definitions and symbols For the purpose of this document, the following terms, defin
32、itions and symbols apply. 2.1 Terms and definitions 2.1.1 highest voltage of a system U shighest value of operating voltage which occurs under normal operating conditions at any time and any point in the system (phase to phase voltage) NOTE Transient overvoltages due e.g. to switching operations and
33、 abnormal temporary variations of voltage are not taken into account. IEV 601-01-23, modified 2.1.2 transient overvoltage short duration overvoltage of few milliseconds or less, oscillatory or non-oscillatory, usually highly damped Page5 EN61472:200467412 IE2:C 400 6 IEV 604-03-13 2.1.3 fifty per ce
34、nt disruptive discharge voltage U 50peak value of an impulse test voltage having a 50 per cent probability of initiating a disruptive discharge each time the dielectric testing is performed IEV 604-03-43 2.1.4 ninety per cent statistical impulse withstand voltage U 90peak value of an impulse test vo
35、ltage at which insulation exhibits, under specified conditions, a 90 % probability of withstand NOTE This concept is applicable to self-restoring insulation. IEV 604-03-42, modified 2.1.5 two per cent statistical overvoltage U 2peak value of a transient overvoltage having a 2 % statistical probabili
36、ty of being exceeded IEV 651-01-23, modified 2.1.6 required insulation level for live working statistical impulse withstand voltage of the insulation at the work location necessary to reduce the risk of breakdown of this insulation to an acceptably low level NOTE It is generally considered that an a
37、cceptable low level is reached when the value of the statistical withstand voltage is greater or equal to the statistical overvoltage having a probability of being exceeded by no more than 2 %. IEV 651-01-17 2.1.7 per unit value u expression of the per unit value of the amplitude of an overvoltage (
38、or of a voltage) referred to U s 2/ 3 NOTE This applies to u e2and u p2defined in Clause 4. 2.1.8 minimum approach distance D Aminimum distance in air to be maintained between any part of the body of a worker, including any object (except appropriate tools for live working) being directly handled, a
39、nd any parts at different potentials NOTE The “appropriate tools” are tools for live working suitable for the maximum nominal voltage of the live parts. Definition 2.7.1 of IEC 60743 and IEV 651-01-20, modified 2.1.9 electrical distance D Udistance in air required to prevent a disruptive discharge b
40、etween energized parts or between energized parts and earthed parts during live working Definition 2.7.2 of IEC 60743 and IEV 651-01-21, modified Page6 EN61472:200467412 IE2:C 400 7 2.1.10 ergonomic distance D Edistance in air to take into account inadvertent movement and errors in judgement of dist
41、ances while performing work Definition 2.7.3 of IEC 60743 and IEV 651-01-22 2.1.11 part any element present in the work location, other than workers, live working tools and system insulation 2.1.12 live part conductor or conductive part intended to be energized in normal operation, including a neutr
42、al conductor, but by convention not a PEN conductor IEV 195-02-12 or PEM conductor IEV 195-02-13 or PEL conductor IEV 195-02-14 NOTE This concept does not necessarily imply a risk of shock. Definition 2.1.2 of IEC 60743 and IEV 651-01-03, modified 2.1.13 work location any site, place or area where a
43、 work activity is to be, is being, or has been carried out IEV 651-01-08 2.2 Symbols used in the normative part of the document ratio of the total length of the floating object(s) to the original air gap length D length of the remaining air gap phase to earth D Aminimum approach distance D Eergonomi
44、c distance D Uelectrical distance necessary to obtain U 90d 1 , d 2 , d 3,d 4distances between the worker(s) and parts of the installation at different electric potentials (see Figure 2) F sum of all dimensions, in the direction of the gap axis, of the floating objects in the air gap (in metres) K s
45、statistical safety factor K tfactor combining different considerations influencing the strength of the gap k aatmospheric factor k dcoefficient characterizing the average state of the damaged units k ffloating object factor k ggap factor Page7 EN61472:200467412 IE2:C 400 8 k iinsulator strings facto
46、r k sstandard statistical deviation factor L foriginal air gap length n dnumber of damaged units in a string of n ounits n onumber of units in an insulator string that are not shunted by arcing horns or grading rings P length of the remaining gap phase to phase r distance of a conductive object from
47、 the axis of the gap s enormalized value of the standard deviation of U 50expressed in percent U 2two per cent statistical overvoltage U 50fifty per cent disruptive discharge voltage U 90ninety per cent statistical impulse withstand voltage U e2two per cent statistical overvoltage between phase and
48、earth U e90ninety per cent statistical impulse withstand voltage phase to earth U p2two per cent statistical overvoltage between two phases U p90ninety per cent statistical impulse withstand between two phases u e2per unit value of the two per cent statistical overvoltage phase to earth u p2per unit
49、 value of the two per cent statistical overvoltage between two phases U shighest voltage of a system between two phases 3 Methodology The methodology of the calculation of the minimum approach distances is based on three considerations: a) to determine the statistical overvoltage expected in the work location (U 2 ) and from
