1、BRITISH STANDARD BS EN 50068:1991 Incorporating Amendment No. 1 Specification for Wrought steel enclosures for gas-filled high-voltage switchgear and controlgear This European Standard EN50068:1991 has the status of a British StandardBSEN50068:1991 This British Standard, having been prepared under t
2、he directionof the Power ElectricalEngineering StandardsPolicy Committee, waspublished underthe authorityof the Standards Boardand comes intoeffect on 30September1991 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference PEL/92 Draft announced in BSI News
3、December 1988 ISBN 0 580 19622 4 Cooperating organizations The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises the National Committees of the following countries: Austria Luxemburg Belgium Netherlands Denmark N
4、orway Finland Portugal France Spain Germany Sweden Greece Switzerland Iceland United Kingdom Ireland Italy Amendments issued since publication Amd. No. Date Comments 8054 January 1994 Indicated by a sideline in the marginBSEN50068:1991 BSI 12-1999 i Contents Page Cooperating organizations Inside fro
5、nt cover National foreword ii Foreword 2 Text of EN 50068 5 National appendix NA (informative) Inside back cover National appendix NB (informative) Inside back coverBSEN50068:1991 ii BSI 12-1999 National foreword This British Standard has been prepared under the direction of the Power Electrical Eng
6、ineering Standards Policy Committee and is the English language version of EN50068:1991 and its AmendmentA1:1993 “Wrought steel enclosures for gas-filled high-voltage switchgear and controlgear” published by the European Committee for Electrotechnical Standardization (CENELEC). National appendix NA
7、gives the constitution of the committees responsible for UK participation in the preparation of this standard. National appendix NB gives details of International Standards quoted in this standard for which there is an identical or technically equivalent British Standard. A British Standard does not
8、 purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside fr
9、ont cover, pagesi andii, theEN title page, pages2 to70, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROP
10、ISCHE NORM EN50068 February 1991 + A1August 1993 UDC 621.316.54-213.34-034.14 Descriptors: Enclosure, high-voltage switching device, H.V.metal enclosed switchgear and controlgear, pressurized closure, wrought steel English version Wrought steel enclosures for gas-filled high-voltage switchgear and c
11、ontrolgear (includes amendment A1:1993) Enveloppes en acier soud pour lappareillage haute tension sous pression de gaz (inclutlamendment A1:1993) Kapselungen aus Schmiedestahl fr gasgefllteHochspannungs- Schaltgerte und -Schaltanlagen (enthltnderungenA1:1993) This European Standard was approved by C
12、ENELEC on5March1990. CENELEC members are bound to comply 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 stand
13、ards may be obtained on application to the Central Secretariat 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 noti
14、fied to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxemburg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and
15、 UnitedKingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1991 Copyright reserved to CENELEC members Ref. No. EN 50068:1991
16、+ A1:1993 EEN50068:1991 BSI 12-1999 2 Foreword At the request of CENELEC Technical Committee TC17C, the text of the draft EN50068 prepared by TC17C was submitted to the Unique Acceptance Procedure (UAP). The text of the draft was approved by CENELEC as EN50068 on5 March1990. The following dates were
17、 fixed: For products which have complied with the relevant national standard before1991-06-01, as shown by the manufacturer or by a certification body, this previous standard may continue to apply for production until1996-06-01. This document forms a supplement to EN50052(1986): “Cast aluminium allo
18、y enclosures for gas-filled high-voltage switchgear and controlgear” and EN50064 (1989): “Wrought aluminium and aluminium alloy enclosures for gas-filled high-voltage switchgear and controlgear”, concerning welded enclosures for the same type of switchgear and controlgear but composed of parts made
19、of wrought steel. It is based on the general specifications given in HD358S2 (IEC517 (1986) ed 2) which are however not sufficient to satisfy the conditions for the service allowance of pressurized high-voltage switchgear and controlgear.) These specifications are appropriate for pressurized switchg
20、ear enclosures allowing an economic production without sacrificing aspects of safety. For unusual shapes dictated by electrical conditions they permit the verification of sound design by proof tests instead of calculations. Nevertheless this European Standard makes use of many internationally well a
21、cknowledged calculation rulesand the Technical Committee will in additionpursue the progress in standardization in CEN/TC121 and ISO/TC44 on welding and allied processes. For the time being reference can only be made to published International Standards as far as they are appropriate for the purpose
22、 of production of enclosures to be used in gas-filled switchgear and controlgear. The present EN has been established as an international specification for the design, construction, testing, inspection and certification of pressurized enclosures used in high-voltage switchgear and controlgear. This
23、standard followsto that extent also Article2 of the Directive76/767/EEC. The European Standard contains two normative and one informative technical annexes: Annex A: Welding procedure and welder performance tests. Annex B: Sample of record form. Annex C: National deviations. List of standards referr
24、ed to in this standard: Foreword to Amendment A1 This amendment was prepared by CENELEC Technical Committee TC17C, High-voltage enclosed switchgear and controlgear. The text of the draft was submitted to the voting procedure in March1993 and was approved by CENELEC as amendment A1 to EN50068:1991 on
25、 July6,1993. The following dates were accepted: latest date of publication of an identical national standard (dop) 1991-06-01 latest date of withdrawal of conflicting national standards (dow) 1991-06-01 HD 358 S2 (IEC517(1986) ed 2) Gas-insulated metal-enclosed switchgear for rated voltages of72,5kV
26、 and above ISO 6213:1983 Welding: Items to be considered to ensure quality in welding structures ISO 9000:1987 Guidelines for selection and use of the standards on quality management, quality system elements and quality assurance ISO/IEC Guide 2:1986 General terms and their definitions concerning st
27、andardization and related activities ISO 6520:1982 Classification of imperfections in metallic fusion welds, with explanations ISO/R 373:1964 General principles for fatigue testing of metals latest date of publication ofan identical national standard (dop) 1994-10-01 latest date of withdrawal ofconf
28、licting national standards (dow) 1994-10-01EN50068:1991 BSI 12-1999 3 Text of amendment 2.1 Type of equipment (page 5) The first paragraph has to be changed as follows (new text in bold letters); . . . of high-voltage switchgear and controlgear, where the gas is used principally for its dielectric a
29、nd/or arc-quenching properties, with rated voltages. 1 kV and up to and including 52 kV and with gas-filled compartments with design pressure greater than3 bar (gauge); and with rated voltage 72,5 kV and above. Annex C (page 67) only English version Clause7.5.3.2, Italy: The formula for “B” has to b
30、e corrected as follows: Contents Page Foreword 2 1 Introduction 5 2 Scope and field of application 5 3 Definitions 6 4 Materials 7 5 Design 7 6 Manufacture and workmanship 40 7 Inspection and testing 46 8 Pressure relief devices 53 9 Certification and marking 53 Annex A Welding procedure and welder
31、performance tests 55 Annex B Sample of record form 65 Annex C (informative) National deviations 67 Figure 1 to Figure 4 Typical connections betweencylindrical and conical shells 11 Figure 5 Design factor and numerical factor 1/cos 13 Figure 6 Dished end 15 Figure 7 Dished end with branch 15 Figure 8
32、 Dished end with knuckle and crown of unequal wall thickness 15 Figure 9 Welded joint outside 0,6D a : v = 0,75 resp. 1,0 16 Figure 10 Welded joint inside 0,6D a : v = 1,0 16 Figure 11 Welded dished end from crown and knuckle components inside 0,6D a : v = 1,0 17 Figure 12 Welded dished end from cro
33、wn and knuckle components outside 0,6D a : v = 0,75 resp. 1,0 17 Figure 13 Design factor for dished ends of the Klpper type 19 Figure 14 Design factor for dished ends of the Korbbogen type 19 Figure 15 Determination of the buckling pressure 20 Figure 16 Increased thickness of a cylindrical shell 21
34、Figure 17 Increased thickness of a conical shell 21 Figure 18 Local increase by reinforcement rings 21 Figure 19 Pad reinforcement 21 Figure 20 Branch reinforcement 22 B K 4,8 - =EN50068:1991 4 BSI 12-1999 Page Figure 21 Necked out opening 22 Figure 22 Calculation scheme for cylindricalshells 23 Fig
35、ure 23 Calculation scheme for sphericalshells 24 Figure 24 Calculation scheme for adjacent branches in longitudinal direction of a cylinder 24 Figure 25 Calculation scheme for adjacent branches in a sphere or in circumferential direction of a cylinder 25 Figure 26 Branch and pad reinforcement 26 Fig
36、ure 27 Weakening factor v Afor openings and branches perpendicular to cylindrical and conical shells 27 Figure 28 Weakening factor v Afor openings and branches perpendicular to spherical shells 28 Figure 29 Circular flange joint 29 Figure 30 Examples of different flange types 31 Figure 31 Forces and
37、 moment arms for flanges with O-ring seal 32 Figure 32 Hubless flange sections for stress calculation 32 Figure 33 Flange with untapered hub section for stress calculation 33 Figure 34 The factor “A” as a function of K 1and K 2 35 Figure 35 Graph showing in (D y /D i ) as a function of m = D y /D i
38、36 Figure 36 Forces and moment arms for flanges with O-ring seal 37 Figure 37 Flange with large fillet radius sections for stress calculation 38 Figure 38 Flange with tapered hub sections for stress calculation 39 Figure 39 Flange with flat circular cover and O-ring seal 40 Figure 40 Butt welds in p
39、lates of unequal thickness with approximately coincident middle lines 47 Figure 41 Butt welds in plates of unequal thickness with offset of middle lines 48 Figure A.1 Test piece for butt weld in plate 59 Figure A.2 Test piece for butt weld in pipe 59 Page Figure A.3 Test piece for fillet weld in pla
40、te 61 Figure A.4 Test piece for branch connection in pipe 63 Figure A.5 Dimensions of tensile test specimen from pipe of outside diameter greater than 35 mm 64 Table 1 Examples of materials (not exhaustive; other steels may be used from national standards) 8 Table 2 Design factor for conical shells
41、and numerical factors cos and 1/cos 13 Table 3 The factor “A” as a function of K 1and K 2 35 Table 4 Values of “ln m” as function of “m” 36 Table 5 Circumferential tolerances 43 Table 6 Circularity tolerances for shells 43 Table 7 Acceptance levels for imperfections 50 Table A.1 57 Table A.2 Number
42、of test specimens required 60EN50068:1991 BSI 12-1999 5 1 Introduction This standard covers the requirements for the design, construction, testing, inspection and certification ofgas-filled enclosures for use specifically in high-voltage switchgear and controlgear or for associated gas-filled equipm
43、ent. Special consideration is given to these enclosures for the following reasons. a) The enclosures usually form the containment of electrical equipment, thus their shape is determined by electrical rather than mechanical considerations. b) The enclosures are installed in restricted access areas an
44、d the equipment is operated by experts and instructed persons only. c) As the thorough drying of the inert, non-corrosive gas-filling medium is fundamental to the satisfactory operation of the electrical equipment it is periodically checked. For this reason, no internal corrosion allowance is requir
45、ed on the wall thickness of these enclosures. d) The enclosures are subjected to only small fluctuations of pressure as the gas-filling density shall be maintained within close limits to ensure satisfactory insulating and arc-quenching properties. Therefore, the enclosures are not liable to fatigue
46、due to pressure cycling. e) The operating pressure is relatively low. For the foregoing reasons, and to ensure the minimum disturbance hence reducing the risk of moisture and dust entering the enclosures which would prevent correct electrical operation of the switchgear, no pressure tests shall be c
47、arried out after installation and before placing in service and no periodic inspection of the enclosure interiors or pressure tests shall be carried out after the equipment is placed in service. 2 Scope and field of application 2.1 Type of equipment This standard applies to fusion welded wrought ste
48、el enclosures pressurized with dry air, inert gases, for example sulphur hexafluoride or nitrogen or a mixture of such gases, used in indoor or outdoor installationsof high-voltage switchgear and controlgear with rated voltages 72,5 kV and above, where the gas is used principally for its dielectric
49、and/or arc-quenching properties. The enclosures comprise parts of electrical equipment not necessarily limited to the following examples: Circuit-breakers Switch-disconnectors Disconnectors Earthing switches Current transformers Voltage transformers Surge arrestors Busbars and connections The scope also covers pressurized components such as the centre chamber of live tank switchgear, gas-insulated current transformers, etc. 2.2
