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1、BRITISH STANDARD BS 5501-8: 1988 EN 50 028: 1987 Incorporating Amendment No. 1 Electrical apparatus for potentially explosive atmospheres Part 8: Encapsulation “m” European Standard EN 50 028 has the status of a British Standard. UDC 621.3-2.13.34:614.838.4:620.1 BS 5501-8:1988 This British Standard
2、, having been prepared under the direction of the General Electrotechnical Engineering Standards Committee, was published under the authority of the Board of BSI on 29 January 1988 BSI 01-1999 The following BSI references relate to the work on this standard: Committee reference GEL/114 Draft for com
3、ment 80/26971 DC ISBN 0 580 16544 2 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. Summary of pages This document comprises a f
4、ront cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 16, 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. AustriaLu
5、xemburg BelgiumNetherlands DenmarkNorway FinlandPortugal FranceSpain GermanySweden GreeceSwitzerland IrelandUnited Kingdom Italy Amendments issued since publication Amd. No.Date of issueComments 6439March 1990Indicated by a sideline in the margin BS 5501-8:1988 BSI 01-1999i Contents Page Cooperating
6、 organizationsInside front cover Text of EN 50 0285 National appendix A16 National appendix BInside back cover ii blank EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 50 028 February 1987 UDC:621.3-2.13.34:614.838.4:620.1 Key words: Electrical apparatus, potentially explosive atmosphere, explo
7、sive atmosphere, explosion protection, specific requirement, encapsulation “m” English version Electrical apparatus for potentially explosive atmospheres Encapsulation “m” Matriel lectrique pour atmosphres explosibles Encapsulage “m” Elektrische Betriebsmittel fr explosionsgefhrdete Bereiche Verguss
8、kapselung “m” This European Standard was ratified by CENELEC on 10 September 1986. CENELEC members are bound to comply with the requirements of the CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
9、Up-to-date list and bibliographical references concerning such national standards may be obtained on application to the CENELEC General 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 tr
10、anslation under the responsibility of a CENELEC member into its own language and notified to CENELEC General Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland,
11、 Italy, Luxemburg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung General Secretariat: rue Brderode 2, B-100
12、0 Brussels CENELEC 1987 Copyright reserved to all CENELEC members Ref. No. EN 50 028:1987 E EN 50 028 BSI 01-1999 2 Contents Page IEC Publications referred to in European Standard EN 50 0283 European Standards referred to in European Standard EN 50 0283 Section 1. General 1Object and field of applic
13、ation5 2Definitions5 2.1Encapsulation “m”5 2.2Compounds5 2.3Temperature range of the compound5 2.4Continuous operating temperature of the compound5 2.5Encapsulation5 2.6Embedding5 2.7Potting5 Section 2. Requirements for compounds and construction 3Requirements for compounds5 4Constructional requirem
14、ents6 4.1General6 4.2Thickness of the layer of compound7 4.3Distances through the compound7 4.4Temperature limitation7 4.5External connections7 4.6Protection of bare live parts8 4.7Adhesion8 4.8Primary and secondary cells, batteries and accumulators8 4.9Fuses8 Section 3. Verification and tests 5Gene
15、ral8 6Type tests9 6.1Tests for compounds9 6.2Tests for encapsulated electrical apparatus, encapsulated parts of electrical apparatus and encapsulated Ex components9 7Routine tests11 7.1Visual check11 7.2Electric strength test11 7.3Checking the electrical data11 7.4Voltage transformers11 Page Section
16、 4. Marking 8Marking11 8.1Marking of electrical apparatus11 8.2Marking of Ex components12 Annex A Test procedure during thermal cycling tests according to 6.2.1.213 Annex B (Supplementary information) Order of type tests14 Table 1 Minimum distances through the compound7 EN 50 028 BSI 01-19993 IEC Pu
17、blications referred to in European Standard EN 50 028 IEC 44-4 (1980) (1st Edition), Instrument transformers Part 4: Measurement of partial discharges. IEC 127 (1974) (2nd Edition), Cartridge fuse-links for miniature fuses. (HD 109 S3) IEC 269-1 (1968), Low voltage fuses Part 1: General requirements
18、. IEC 269-2 (1973), Low voltage fuses Part 2: Supplementary requirements for fuses for industrial applications. IEC 269-2A (1975) First supplement, Appendix A Examples of standardized fuses for industrial applications. IEC 269-2A (1978), Amendment No. 1. IEC 269-3 (1973), Low voltage fuses Part 3: S
19、upplementary requirements for fuses for domestic and similar applications. IEC 269-3 (1978), Amendment No. 1. IEC 269-3A (1978), First supplement. Appendix A Examples of standardized fuses for domestic and similar applications. IEC 269-4 (1980), Low voltage fuses Part 4: Supplementary requirements f
20、or fuse links for the protection of semi-conductor devices. European Standards referred to in European Standard EN 50 028 EN 50 014 (1977) (1st edition), Electrical apparatus for potentially, explosive atmospheres General requirements including Amendment 1 (July 1979), Amendment 2 (June 1982), Amend
21、ment 3 (December 1982), Amendment 4 (December 1982) and Amendment 5 (February 1986). EN 50 019 (1977) (1st edition), Electrical apparatus for potentially explosive atmospheres Increased safety “e” including Amendment 1 (July 1979), Amendment 2 (September 1983) and Amendment 3 (December 1985). EN 50
22、020 (1977) (1st edition), Electrical apparatus for potentially explosive atmospheres Intrinsic safety “i” including Amendment 1 (July 1979) and Amendment 2 (December 1985). 4 blank EN 50 028 BSI 01-19995 Section 1. General 1 Object and field of application 1.1 This European Standard contains the spe
23、cific requirements for construction and testing of electrical apparatus, parts of electrical apparatus and Ex components in the type of protection encapsulation “m”, intended for use in potentially explosive atmospheres. 1.2 This European Standard applies to electrical apparatus, parts of electrical
24、 apparatus and Ex components which have rated voltages not exceeding 11 kV. 1.3 This European Standard supplements European Standard EN 50 014 “General requirements”, with the following exceptions. 2 Definitions The following definitions specific to type of protection encapsulation “m” are applicabl
25、e to this European Standard; they supplement the definitions which are given in European Standard EN 50 014 “General requirements”. 2.1 encapsulation “m” a type of protection in which the parts which could ignite an explosive atmosphere by either sparking or heating are enclosed in a compound in suc
26、h a way that this explosive atmosphere cannot be ignited 2.2 compounds thermosetting, thermoplastic and elastomeric materials with or without fillers and/or additives, are considered after their solidification to be compounds 2.3 temperature range of the compound the range of temperatures within whi
27、ch the properties of the compound, in either operation or storage, permit the compliance with the requirements of this European Standard 2.4 continuous operating temperature of the compound the maximum temperature to which the compound can be subjected continuously according to the data given by the
28、 manufacturer of the compound 2.5 encapsulation the process of applying the compound to enclose electrical device(s) by suitable means such as embedding or potting 2.6 embedding the process of completely encasing electrical device(s) by pouring a compound over it in a mould, and removing the enclose
29、d device from the mould after solidification of the compound 2.7 potting an embedding process in which the mould remains attached to the encased electrical device(s) Section 2. Requirements for compounds and construction 3 Requirements for compounds 3.1 The documents presented by the manufacturer an
30、d verified by the testing station in accordance with 22.2 of European Standard EN 50 014 “General requirements” shall describe precisely the compound(s) used as well as the production method during encapsulation. Clauses of European Standard EN 50 014 which are not applicable 4.1Maximum surface temp
31、erature (for Ex components) 5.2Time delay before opening an enclosure 6.1Definition of the enclosure material 6.2 (first paragraph) Temperature index TI 6.4Threaded holes in enclosures of plastic material 8Fasteners 9Interlocking devices 15Cable and conduit entries 17Switchgear 18Fuses 20.2Warning l
32、abel for luminaires 22.4.3.1Impact tests (for Ex components) 22.4.4Tests for degree of protection for enclosures 22.4.8Tests in explosive mixtures 22.4.9Tests of clamping of non-armoured cables in cable entries 22.4.10Tests of clamping of armoured cables in cable entries EN 50 028 6 BSI 01-1999 3.2
33、The description shall include: the name and address of the manufacturer of the material; the exact and complete reference of the material, its colour as well as the kind and percentage of fillers and other additives, when they are included; NOTEAn ISO designation should be used where possible surfac
34、e treatments, such as varnishes etc., where they are used; the temperature range of the compound(s); the continuous operating temperature of the compound. 3.3 The testing station is not required to verify compliance of the material with its description. 4 Constructional requirements 4.1 General 4.1.
35、1 The choice of the compound(s) to be used for a specific application is dependent on the task each compound has to perform. Only the properties of the compound(s) on which the type of protection “m” depends shall be taken into account. The requirements of 6.3 (Electrostatic charges of enclosures of
36、 plastics material) of European Standard EN 50 014 apply to the surface of the compound in encapsulated electrical apparatus or encapsulated parts of electrical apparatus or encapsulated Ex components when such a surface is freely exposed to the environment. The requirements of 6.3 of European Stand
37、ard EN 50 014 do not apply when encapsulated parts of electrical apparatus or encapsulated Ex components are designed to be mounted within an additional enclosure. 4.1.2 The encapsulation shall be made without voids, but it is permitted to encapsulate components (relays, transistors, etc.) with inte
38、rnal voids up to 100 cm3. The thickness of compound between such components shall be at least 3 mm; where the void is less than 1 cm3 the thickness of the compound may be reduced to 1 mm. Switching contacts shall have an additional housing before encapsulation. If the rated contact current exceeds 6
39、 A, the additional housing shall be inorganic. 4.1.3 Encapsulated electrical apparatus, encapsulated parts of electrical apparatus, or encapsulated Ex components designed to be connected to an external source of supply shall be suitable for a prospective short circuit current of 4 000 A unless the m
40、arking includes the value of the permitted prospective short circuit current. 4.1.4 The type of protection encapsulation “m” shall be maintained even in the case of recognized overloads and any single internal electrical fault which could cause either an overvoltage or overcurrent, for example: shor
41、t circuit of any component; open circuit due to any component failure; fault in the printed circuitry; etc. NOTEIf a fault can lead to one or more subsequent faults, e.g. overrating of a component, the primary and subsequent faults are considered to be a single fault. Components as specified in 4.1.
42、5 of this European Standard are considered as not subject to fault. Distances as specified in 4.3 of this European Standard are considered as not subject to fault. For criteria of acceptance see 6.2.1.3 of this European Standard. 4.1.5 The following components shall be considered as not subject to f
43、ault when encapsulated in accordance with this European Standard: film type resistors; wire resistors with single layer in helical form; coils with single layer in helical form; plastic foil capacitors; paper capacitors; ceramic capacitors when they are used at no more than 2/3 of their rated voltag
44、e and power as specified by the manufacturer of the respective components. optocouplers designed for segregation of different circuits, when: a) the sum U of the r.m.s, values of the voltages of the two circuits is not more than 1 000 V and b) the rated voltage of the optocouplers determined in acco
45、rdance with 6.2.4 of this European Standard is at least 1,5 times U. transformers, coils and motor-windings, which comply with European Standard EN 50 019 “Increased safety “e” including those that use wire sizes less than 0,25 mm diameter and which are also protected against inadmissible internal t
46、emperatures; transformers which comply with 7.1 of European Standard EN 50 020 “Intrinsic safety “i” except those of type 2(a) of 7.1.2. EN 50 028 BSI 01-19997 4.1.6 The fixing of the encapsulated electrical apparatus, encapsulated parts of electrical equipment or encapsulated Ex component shall not
47、 affect the type of protection encapsulation “m”. 4.2 Thickness of the layer of compound 4.2.1 The thickness of the compound between the free surface of the compound and the components/conductors in the encapsulation shall be at least 3 mm. However, for very small encapsulated electrical apparatus,
48、encapsulated parts of electrical apparatus or encapsulated Ex components having no free surface exceeding 2 cm2, a thickness of at least 1 mm is allowed. If in this case the impact test according to European Standard EN 50 014 “General requirements” or the electric strength test of 6.2.4 of this Eur
49、opean Standard cannot be passed on the encapsulated electrical apparatus or encapsulated parts of electrical apparatus, the testing station shall issue a certificate having the sign “x” and requiring other means of protection, e.g. an additional mechanical protection. 4.2.2 Where the encapsulated electrical apparatus, encapsulated parts of the electrical apparatus or the encapsulated Ex component includes a metal protective housing (potting), the thickness of the layer between the housing and any component or conductor shall be at least 1