1、BRITISH STANDARD BS EN 50375:2002 Testing methodology for wipers used in electrical insulating oil The European Standard EN 50375:2002 has the status of a British Standard ICS 29.040.10 BS EN 50375:2002 This British Standard, having been prepared under the direction of the Electrotechnical Sector Po
2、licy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 10 October 2002 BSI 10 October 2002 ISBN 0 580 40554 0 National foreword This British Standard is the official English language version of EN 50375:2002. The UK participation in its prepa
3、ration was entrusted to Technical Committee GEL/10, Fluids for electrotechnical applications, 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 Eu
4、ropean publications 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
5、 all the necessary 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 enquirie
6、s on the interpretation, 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 16, an inside back
7、 cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD EN 50375 NORME EUROPENNE EUROPISCHE NORM August 2002 CENELEC European Committee for Electrotechnical Sta
8、ndardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 50375:20
9、02 E ICS 29.040.10 English version Testing methodology for wipers used in electrical insulating oil Mthodologie dessai des moyens de nettoyage utiliss dans les huiles isolantes usages lectriques Prfmethoden fr Putzlappen, die fr Isolierl verwendet werden This European Standard was approved by CENELE
10、C on 2002-03-05. 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 standards
11、 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 notified
12、 to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, S
13、lovakia, Spain, Sweden, Switzerland and United Kingdom.EN 50375:2002 - 2 - Foreword This European Standard has been prepared by CENELEC BTWG 99-1, Insulating oil. The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 50375 on 2002-03-05. The followi
14、ng dates were fixed: - latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2003-03-01 - latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2005-03-01 Annexes designate
15、d “normative“ are part of the body of the standard. In this standard, annexes A, B, C, D and E are normative. Warning: This European Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitabili
16、ty and does not absolve the user from legal obligations relating to health and safety at any stage. 3 EN 50375:2002 Contents Introduction 4 1 Scope 5 2 Normative references.5 3 Terms and definitions.5 4 Test methods.6 4.1 Fibre release test (refer to annex A)6 4.2 Snagging test (refer to annex B) .6
17、 4.3 Equilibrium moisture content (refer to annex C) 6 4.4 Oil absorbency (refer to annex D and annex E)6 5 Test report .7 Annex A (normative) Fibre release from wipers8 Annex B (normative) The snagging test12 Annex C (normative) Equilibrium moisture content of wipers14 Annex D (normative) Oil absor
18、bency of wipers.15 Annex E (normative) Rate of absorbency .16 Figure A.1 Schematic arrangement of suitable apparatus for fibre release test .9 Figure B.1 Test board for snagging test 12 Figure B.2 Schematic arrangement of scratch pattern on wiper after snagging test.13EN 50375:2002 - 4 - Introductio
19、n Fibres and other particles have a detrimental effect on the dielectric strength of insulating oil. During the maintenance of electrotechnical equipment it is often necessary to use a wiper or cloth to clean components or absorb oil. To minimize contamination by fibres and resultant degradation of
20、oil properties, it is necessary to make a selection of the type of wiper used in this application. The properties required of wipers for use with insulating oil are as follows: low fibre release; fibres released from a wiper should have the least possible effect on the dielectric strength of insulat
21、ing oil; high tear resistance; should tearing occur, subsequent fibre release should be low; oil absorbency should ideally be high; the wipers should have no other effect which degrades the properties of insulating oil below those required by IEC 60296. 5 EN 50375:2002 1 Scope This European Standard
22、 specifies testing procedures for fibrous wipers to be used with equipment normally containing electrical insulating oil. Such testing is necessary to rank commercial products, so that possible contamination of insulating oil and electrical equipment with fibres during maintenance operations may be
23、minimized. 2 Normative references This European Standard incorporates, by dated or undated reference, provisions from other standards. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to
24、or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 50353 Insulating oil - Determination of fibre contamination by the counting method usi
25、ng a microscope EN 60156 Insulating liquids - Determination of the breakdown voltage at power frequency - Test method (IEC 60156) EN 60814 Insulating liquids - Oil-impregnated paper and pressboard - Determination of water by automatic coulometric Karl Fischer titration (IEC 60814) IEC 60296 Specific
26、ation for unused mineral insulating oils for transformers and switchgear ISO 554 Standard atmospheres for conditioning and/or testing - Specifications 3 Terms and definitions For the purposes of this European Standard the following terms and definitions apply. 3.1 standard atmosphere the atmosphere
27、in an enclosure where the temperature is (23 2) C and the relative humidity is (50 2) %. This standard atmosphere is recommended in ISO 554. When conditioning oil, the enclosure shall also be protected from sunlight to minimize oxidation of the oil NOTE This atmosphere may be achieved in an enclosur
28、e containing a vessel of a saturated solution of tetrahydrated calcium nitrate Ca(NO 3) 2.4H 2O. 3.2 conditioned oil unused oil conforming to IEC 60296 which has been filtered through a membrane filter of pore diameter 1,2 m or less into a glass vessel cleaned as described in Clause 7 of EN 50353. T
29、his oil is then stored in standard atmospheric conditions (3.1) for sufficient time to attain equilibrium NOTE 1 It has been found that, if stored in a 3 litre standard tall-form beaker, 72 h is sufficient for oil to attain equilibrium. NOTE 2 Oil conditioned in this manner is expected to have a min
30、imum breakdown strength of 50 kV (measured according to EN 60156) and a maximum water content of 33 mg/kg (measured according to EN 60814).EN 50375:2002 - 6 - 3.3 standard wiper a wiper of dimension 250 mm x 250 mm in the as-received condition with no cut or torn edges made after manufacture. The wi
31、per shall be stored in standard atmospheric conditions (3.1) for sufficient time to attain equilibrium NOTE Manufacturers are advised, for the purpose of testing, to produce standard size wipers (250 mm x 250 mm) on which the edges are representative of those produced in the normal manufacturing pro
32、cess. 4 Test methods The test methods for wipers are detailed in Annexes A to E and are summarized below. NOTE Whilst wipers may perform well in these tests, in normal everyday use they may become contaminated with fibres by contact with their environment and these fibres can then be passed on to co
33、ntaminate the oil. Care should be taken to avoid this. A particular cause for concern is the packaging. To avoid contamination, wipers should be packaged in non-fibre shedding material and the method of dispensing should prevent excessive production of fibres from the wipers or the container. 4.1 Fi
34、bre release test (refer to Annex A) This test simulates the use encountered whilst wiping during maintenance operations and measures the free fibres produced. For the test to be comparable between different brands of wiper, it is necessary to define the dimensions of the laboratory equipment used du
35、ring the fibre release test. A standard wiper (3.3) must be tested in standard laboratory equipment. In annex A the dimensions of suitable apparatus are defined. 4.2 Snagging test (refer to Annex B) Equipment being wiped often has sharp corners or edges and during use snagging or tearing of the wipe
36、r may occur, with subsequent increased fibre release from the torn part of the wiper. This test is designed to establish the increased number of fibres released by snagging a wiper on a standard array of sharp points. 4.3 Equilibrium moisture content (refer to Annex C) Reduction of the dielectric st
37、rength of oil containing fibres is lessened if these fibres have low equilibrium moisture content. The test measures the equilibrium moisture content of a wiper. NOTE: Natural fibres have greater equilibrium moisture contents than man-made fibres and it is for this reason that wipers made of natural
38、 fibres such as cotton, wool or cellulose (paper) cannot be recommended for this application. 4.4 Oil absorbency (refer to Annex D and Annex E) Wipers are mostly used for cleaning components and mopping up spillages. They should be able to absorb sufficient quantities of oil at a rate suitable for t
39、he application. A measurement is made of the amount of oil capable of being absorbed by a wiper and the rate at which it is absorbed. 7 EN 50375:2002 5 Test report The test report shall contain the following information: a) reference to this European Standard; b) full description of sample under tes
40、t, including name of wiper, manufacturer and description of fibre type (if possible); c) breakdown strength of the oil used to carry out test A: initial value; value after the blank test; value after testing the fibre release from the sample; d) number and size distribution of fibres released per sq
41、uare metre of wiper in the fibre release test (Annex A); e) number and size distribution of fibres released per square metre of wiper after the snagging test (Annex B); f) equilibrium moisture content of wiper (Annex C); g) oil absorbency of wiper (Annex D); h) rate of absorbency of two defined test
42、 samples (Annex E); i) date of the test. NOTE This standard comprises a variety of tests. Individual users may apply different weightings to each test to produce a ranking or grading for their application. The suitability of any wiper for a particular application is a matter of agreement between use
43、r and supplier.EN 50375:2002 - 8 - Annex A (normative) Fibre release from wipers A.1 Principle This test simulates the use encountered whilst using a wiper during maintenance operations. A standard wiper (3.3), conditioned in standard atmosphere (3.1) is rotated at speed of (120 2) r.p.m. in a close
44、d, pre-cleaned glass vessel containing a quantity of conditioned fibre- free oil (3.2), such that the wiper rubs against the walls of the vessel. A measurement is made of the contamination of the test oil by fibres being shed by the wiper and of the effect on the dielectric strength of the test oil
45、due to contamination from these or other particulate material. A.2 Apparatus A.2.1 Glass vessel assembly, with vessel of capacity of at least 3 litres, internal diameter 130 mm and fitted with a lid containing a hole or slot for a stirrer rod. This vessel shall have a calibrated scale denoting the v
46、olume of the contents ( 5 %). NOTE 1 A 3 litre tall-form beaker has been found suitable. NOTE 2 During stirring it may be necessary to stabilize the glass vessel to prevent its rotation. A.2.2 Stirrer assembly, consisting of motor with rotational speed of (120 2) r.p.m., drive shaft with termination
47、 suitable for clamping a standard wiper (3.3), wiper clamping assembly. NOTE An arrangement found to be suitable is shown in Figure A.1. The drive shaft is terminated with a disc magnet and the wiper is clamped between this magnet and a steel disc. The clamping arrangement shall be such that the wip
48、er assumes a diameter of 75 mm at the clamp. A.3 Preparation of equipment A.3.1 All glassware, lid and stirrer rod shall be cleaned as outlined for glassware in Clause 7 of EN 50353. The equipment shall be free of solvent after cleaning. A.3.2 Condition 2 500 ml of oil, according to 3.2, in the glas
49、s vessel assembly (A.2.1). A.3.3 Measure the moisture content of the oil according to EN 60814. The moisture content shall be in the range (28 5) mg/kg. Determine the breakdown strength according to EN 60156. The breakdown strength shall be greater than 50 kV. Report this breakdown strength (initial value). 9 EN 50375:2002127130 mm Key: 8 1 = stirrer motor 2 = stirrer rod 3 = magnetic clamper 6 4 = ste
