BS-5501-4-1977 EN-50017-1977.pdf

BRITISH STANDARD BS 5501-4: 1977 EN 50 017 Incorporating Amendment Nos. 1 and 2 Electrical apparatus for potentially explosive atmospheres Part 4: Powder filling “q” This European Standard EN 50 017 was given as from 30 December 1977 the status of a British Standard UDC 621.31 213.34 78:614.833.4/.5:001.4:620.1:62 777 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5501-4:1977 This British Standard, having been prepared under the direction of the General Electrotechnical Engineering Standards Committee, was published under the authority of the Executive Board on 30 December 1977 © BSI 02-1999 The following BSI references relate to the work on this standard: Committee reference GEL/114 Draft for comment 75/23941 DC ISBN 0 580 09568 1 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 front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 14 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. AustriaNetherlands BelgiumNorway DenmarkPortugal FinlandSpain FranceSweden GermanySwitzerland IrelandUnited Kingdom Italy Amendments issued since publication Amd. No.Date of issueComments 3236January 1980 6440March 1990Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5501-4:1977 © BSI 02-1999i Contents Page Cooperating organizationsInside front cover Text of EN 50 0173 National appendix A13 National appendix B14 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN 50 017 Edition 1 March 1977 UDC 621.31-213.34-78:614.833.4/.5:001.4:620.1:62-777 Key words: Electrical apparatus potentially explosive atmosphere explosive atmosphere explosion proofing specific requirement powder filling “q” English version Electrical apparatus for potentially explosive atmospheres Powder filling “q” Matériel électrique pour atmosphères explosibles Remplissage pulvérulent “q” Elektrische Betriebsmittel für explosionsgefährdete Bereiche Sandkapselung “q” This European Standard was accepted by CENELEC on 1 March 1977. The CENELEC members are bound to adhere to the CENELEC Internal Regulations which specify under which conditions this European Standard has to be given, without any alteration, the status of a national standard. Up-to-date lists 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 is established by CENELEC in three official versions (English, French, German). A translation made by another member under its own responsibility, in its own language, and notified to CENELEC has the same status. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Ireland, Italy, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung General Secretariat: 2, rue Bréderode, B-1000 Brussels © Copyright reserved to all CENELEC members Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50 017 © BSI 12-19982 IEC Publications referred to in European Standard EN 50 017 IEC 85 (1957) (1st edition), Recommendations for the classification of materials for the insulation of electrical machinery and apparatus in relation to their thermal stability in service. IEC 144 (1963) (1st edition), Degrees of protection for enclosures for low-voltage switchgear and controlgear. ISO Standard referred to in European Standard EN 50 017 ISO 565 (1972) (1st edition), Test sieves Woven metal wire cloth and perforated plate Nominal sizes of apertures. European Standard referred to in European Standard EN 50 017 EN 50 014 (1977) (1st edition), Electrical apparatus for potentially explosive atmospheres General requirements. Contents Page IEC Publications referred to in European Standard EN 50 0172 ISO Standard referred to in European Standard EN 50 0172 European Standard referred to in European Standard EN 50 0172 Section 1. General 1Scope3 2Definitions3 Section 2. Specific constructional requirements 3Enclosure4 4Filling material5 5Use of organic materials5 6Bushings5 7Distances to walls5 8Minimum safe height5 9Use of a screen5 Section 3. Verifications and tests 10Type tests6 11Routine tests6 Section 4. Marking 12Rating plate and operating instructions7 Annex A Determination of minimum safe height or of protection height8 Figure 1 Principle of the type of protection powder filling4 Figure A1 Test apparatus10 Figure A2 Test apparatus with screen11 Figure A3 Fixing of the screen12 Table 1 Distances to walls5 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50 017 3 © BSI 12-1998 Section 1. General This European Standard has been prepared by the CENELEC Technical Committee 31. 1 Scope 1.1 This European Standard contains the specific requirements for the construction and testing of powder-filled electrical apparatus, type of protection “q”, intended for use in potentially explosive atmospheres. 1.2 This European Standard supplements European Standard EN 50 014 “General requirements”, the requirements of which apply to powder-filled electrical apparatus. 1.3 This European Standard applies only to electrical apparatus having a rated voltage less than or equal to 6 600 V and having no moving parts in direct contact with the filling material. 2 Definitions The following definitions specific to type of protection powder filling “q” are applicable in this European Standard; they supplement the definitions which are given in European Standard EN 50 014 “General requirements”. 2.1 type of protection powder filling “q” a type of protection in which the enclosure of electrical apparatus is filled with a material in a finely granulated state so that, in the intended conditions of service, any arc occurring within the enclosure of an electrical apparatus will not ignite the surrounding atmosphere. No ignition shall be caused either by flame or by excessive temperature of the surfaces of the enclosure 2.2 arcing current (Ia) the average value of the r.m.s. current in an arc caused by a short circuit during its development within the filling material of the electrical apparatus 2.3 short circuit current (Icc) the prospective short circuit current, calculated for the point of a network where the powder-filled electrical apparatus is connected 2.4 short circuit time or arcing time (t) the time during which the arcing current Ia flows through the electrical apparatus, counted from its initiation to its final extinction NOTE 1The short circuit arcing current liable to occur at a given point of a network cannot generally be determined experimentally. The experience of certain laboratories shows that the calculated current Icc and the actual arcing current Ia are related, up to 6 kV, as follows: NOTE 2When the electrical apparatus is protected by a circuit breaker, the time t is the total breaking time counted from the beginning of the tripping sequence to the final extinction of current. 2.5 screen a perforated metal sheet fixed inside the enclosure, within the mass of the filling material, in such a way as to cover all the live parts of the electrical apparatus inside the enclosure 2.6 minimum safe height (ho) the shortest vertical distance between the free surface of the filling material, after it is suitably shaken down, and the nearest live parts which prevents transmission of ignition by an electric arc of such current and duration as have been specified for the construction of the electrical apparatus when the electrical apparatus is provided with a screen, the minimum safe height is the sum of the protection height and the height of the reserve layer: ho= hea+ d 2.7 protection height (hea) the distance between the screen and the nearest live part of the electrical apparatus inside the enclosure (see Figure 1) 2.8 height of reserve layer (d) the thickness of the filling material above the screen, designed to fill up any accidentally formed voids in the safety layer (see Figure 1) Icc Ia -1.3 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50 017 © BSI 12-19984 Section 2. Specific constructional requirements 3 Enclosure Enclosures shall normally be of metal. Some other materials may, however, be permitted, provided their mechanical and thermal properties and their long-term stability have been verified. They shall be defined with sufficient accuracy to prevent the material from being replaced by another which might have different characteristics. 3.1 Mechanical strength. The enclosure shall be sufficiently strong, with an appropriate factor of safety, to resist the shocks and stresses to which it will be subjected by reason of the nature and usage of the enclosed apparatus. The mechanical strength is checked by a hydraulic test made in accordance with section 3. 3.2 Degree of protection of the enclosure. The enclosure in its normal service condition, i.e. with all openings closed as in normal use, shall comply with degree of protection IP 54 as defined in IEC 144. 3.3 Filling. Filling shall be carried out so as not to leave any voids within the filling material. Any empty space liable to occur in service above the filling level shall be as small as possible. If voids can occur, they shall be capable of being detected as soon as possible after their occurrence. For this purpose one or more devices which require neither the enclosure to be opened nor the use of special tools shall enable the presence of voids to be detected. 3.4 Insulation of enclosed apparatus. Windings within the enclosure shall be suitably insulated irrespective of the additional insulating effect of the filling material. Their insulation classes shall be defined in accordance with IEC 85. NOTEThe screen completely surrounds the protected electrical apparatus only when the electrical apparatus is designed to operate in any position. Figure 1 Principle of the type of protection powder filling Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50 017 5 © BSI 12-1998 3.5 Means of closing. Special fasteners in accordance with European Standard EN 50 014 “General requirements” shall be used for Group I electrical apparatus. 4 Filling material The filling material shall meet certain technical requirements as regards its electric strength, degree of purity and preparation. 4.1 Quartz. If quartz is used as the filling material, it shall comply with the following requirements. 4.1.1 Size of granules. The size of granules shall lie within the following sieve limits: upper limit: woven wire cloth or perforated plate with nominal mesh apertures of 1.6 mm, lower limit: woven wire cloth with nominal apertures of 250 4m, according to the definitions in ISO 565. 4.1.2 Packing. When filling the enclosure, the filling material shall be suitably shaken down. Partitions, baffles or any other structures which might facilitate the formation of voids or impede packing during the filling process are to be avoided. 4.1.3 Humidity. At the time of filling, the filling material shall not contain more than 0.1 % by weight of water. Furthermore, care shall be taken to avoid any impurity which might reduce the electric strength of the filling material or affect the enclosed electrical apparatus. 4.2 Filling materials other than quartz. Filling materials other than quartz may be used if they satisfy the requirements of this European Standard. 5 Use of organic materials No part made of any organic material shall be used within the layer of filling material above the live parts, or between them and the walls of the enclosure. 6 Bushings Bushings for the entry of conductors shall be such as to ensure that the degree of protection of the enclosure specified in 3.2 is maintained. In addition, they shall be capable of withstanding without damage the stress due to the arcing current Ia as specified for the construction. 7 Distances to walls 7.1 Bare live parts shall be suitably spaced from each other and from the walls of the enclosure. In any case, the minimum distances shall be not less than the limits given in Table 1: between bare live parts or between a bare live part and an internal part of the electrical apparatus at earth potential, and between an insulated winding and the nearest point of the wall of the enclosure (column A of Table 1); between a bare live part and the nearest point of the wall of the enclosure (column B of Table 1). Table 1 Distances to walls 7.2 For electrical apparatus with nominal voltage less than or equal to 500 V and factory-enclosed so as to prevent dismantling without destruction, a distance of 4 mm between live parts, and a distance of 5 mm between live parts and the enclosure are sufficient. 8 Minimum safe height (for electrical apparatus without screens) The minimum safe height (ho) shall be determined by tests made in accordance with the annex but shall be not less than 30 mm for voltages less than or equal to 1 500 V and not less than 50 mm for voltages above 1 500 V. 9 Use of a screen To reduce the minimum safe height, a screen of perforated metal may be inserted within the mass of filling material. If the enclosure is of metal, this screen shall be electrically bonded to it. The screen shall be constructed according to the following requirements. 9.1 Construction. The screen shall consist of a sheet of metal, either stainless or suitably protected against corrosion. It shall be perforated over its whole surface. The holes shall have a diameter of 8 mm to 10 mm, and their centres shall be 50 mm to 70 mm apart. In electrical apparatus having a total volume of less than 25 dm3, the diameters of the holes may be reduced, their spacing varying in the same proportion down to a centre-to-centre spacing of 25 mm for holes with a diameter of 5 mm. Rated voltage Ur.m.s. AB Min.Min. Vmmmm 2501015 6601520 1 1002030 3 3003040 6 6004050 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 12:23:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 50 01