1、BRITISH STANDARDBS EN 60970:2007Incorporating corrigendum January 2008Insulating liquids Methods for counting and sizing particlesICS 17.220.99; 29.040.10g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55
2、g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 60970:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 September 2007 BSI 2008ISBN 978 0 580 61997 7National forewordThis British Standard is the UK implementation of EN 60970:
3、2007, incorporating corrigendum January 2008. It is identical with IEC 60970:2007.The UK participation in its preparation was entrusted to Technical Committee GEL/10, Fluids for electrotechnical applications.A list of organizations represented on this committee can be obtained on request to its secr
4、etary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments/corrigenda issued since publicationDate Comments30 June 2008 Im
5、plementation of CENELEC corrigendum January 2008, deletion of Note in BibliographyEUROPEAN STANDARD EN 60970 NORME EUROPENNE EUROPISCHE NORM August 2007 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechn
6、ische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 60970:2007 E ICS 17.220.99. 29.040.10 English version Insulating liquids - Methods for counting and sizi
7、ng particles (IEC 60970:2007) Isolants liquides - Mthodes de dtermination du nombre et de la taille des particules (CEI 60970:2007) Isolierflssigkeiten - Verfahren zur Bestimmung der Anzahl und Gren von Teilchen (IEC 60970:2007) This European Standard was approved by CENELEC on 2007-08-01. CENELEC m
8、embers 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 may be obtained on applic
9、ation 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 to the Central Secretaria
10、t has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Neth
11、erlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Incorporating corrigendum January 2008Foreword The text of document 10/695/FDIS, future edition 2 of IEC 60970, prepared by IEC TC 10, Fluids for electrotechnical applications, was subm
12、itted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60970 on 2007-08-01. The following 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) 2008-05-01 latest date by which t
13、he national standards conflicting with the EN have to be withdrawn (dow) 2010-08-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 60970:2007 was approved by CENELEC as a European Standard without any modification. _ 2 BS EN 60970:2007CONTENTS INT
14、RODUCTION.4 1 Scope.5 2 Normative references .5 3 General caution, health, safety and environmental protection .5 4 Significance6 5 Comparison and limitation of the methods 6 6 Types and identification of particles7 7 Sampling 7 7.1 General remarks7 7.2 Sampling vessels 8 7.3 Cleaning of sampling bo
15、ttles .8 7.4 General directions for sampling .8 7.5 Sampling procedure . 9 7.6 Labelling of samples. 9 7.6.1 Samples from tanks 9 7.6.2 Samples from electrical equipment . 9 8 Preparation of the samples for analysis . 9 9 Method A Automatic particle size analyzer.10 9.1 Summary of method 10 9.2 Appa
16、ratus and auxiliary materials10 9.3 Calibration procedures 10 9.4 Preparation of the apparatus for counting11 9.5 Preparation of sample before counting 11 9.6 Preparation of sample for counting 11 9.7 Counting procedures .11 9.8 Report .12 9.9 Precision .12 9.10 Repeatability .12 9.11 Reproducibilit
17、y 12 10 Method B Optical microscopy 13 10.1 Principle13 10.2 Procedure by transmitted light.13 10.3 Procedure by incident light 13 Annex A (informative) Use of syringes as sampling vessels .14 Annex B (informative) Calibration of the automatic particle counters 16 Bibliography17 3 Annex ZA (normativ
18、e) Normative references to international publications with theircorresponding European publications 18 BS EN 60970:2007INTRODUCTION The first edition of this standard was published in 1989, and confirmed in 1996. The present edition has been found necessary for consistency with the new ISO 4406:1999
19、, in which calibration procedures for automated particles counters have been changed from ACFTD standard to ISO-MTD standard. Specific procedures for sample preparation are described in more detail when automated particle counters are used. Results and ISO Code reporting are consistent with ISO 4406
20、:1999 standard. Repeatability and reproducibility data are reported. It has been demonstrated that particle contamination of insulating liquids used in electrical equipment have been responsible for major faults 11. Particle analysis is recommended (as complementary test) by IEC 604223 for power tra
21、nsformers with nominal voltage above 170 kV2. Particle counting and sizing is usually carried out using automated counters; the calibration standard for these counters was changed in 1999. The ISO reporting code has also been changed from a two-figure to a three-figure code. This code gives informat
22、ion on three classes of cumulative counting: particles/ml with 4 m, particles/ml with 6 m, particles/ml with 14 m. Particle analysis with automated particle counters has been thoroughly investigated to verify factors influencing the results and to optimize the analysis procedure. Reference figures f
23、or repeatability and Reproducibility are reported, for particle counting and for ISO Class. Annex A provides information about sampling with syringes. Annex B reports a reference for ISO MTD calibration procedure. _ 1Figures in square brackets refer to the bibliography. 4 BS EN 60970:2007INSULATING
24、LIQUIDS METHODS FOR COUNTING AND SIZING PARTICLES 1 Scope This standard describes the sampling procedures and methods for the determination of particle concentration and size distribution. Three methods are specified. One uses an automatic particle size analyser, working on the light interruption pr
25、inciple. The other two use an optical microscope, in either the transmitted light or incident light mode, to count particles collected on the surface of a membrane filter. The optical microscope methods are described in ISO 4407. All three methods are applicable to both used and unused insulating li
26、quids. Annex A contains an alternative sampling procedure using a syringe and Annex B reports a reference for the calibration of automatic particle counters. NOTE 1 The methods are not intended to measure particulate matter in liquids containing sludge. While analysing solid content on oils containi
27、ng sludge refers to method for sediment and sludge determination in IEC 60422, Annex C. NOTE 2 The methods specified are only applicable to measurements related to a limited range of size and number. 2 Normative references The following referenced documents are indispensable for the application of t
28、his document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60475: Method of sampling liquid dielectrics ISO 4406: Hydraulic fluid power Fluids Method for coding the level of contami
29、nation by solid particles ISO 4407: Hydraulic fluid power Fluid contamination Determination of particulate contamination by the counting method using an optical microscope ISO 5884: Aerospace Fluid systems and components Methods for sampling and measuring the solid particle contamination of hydrauli
30、c fluids EN 50353: Insulating oil Determination of fibre contamination by the counting method using a microscope 3 General caution, health, safety and environmental protection This International Standard does not purport to address all the safety problems associated with its use. It is the responsib
31、ility of the user of the standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use. The insulating liquids which are the subject of this standard should be handled with due regard to personal hygiene. Direct contact with the
32、eyes may cause irritation. In the case of eye contact, irrigation with copious quantities of clean running water should be carried out 5 BS EN 60970:2007and medical advice sought. Some of the tests specified in this standard involve the use of processes that could lead to a hazardous situation. Atte
33、ntion is drawn to the relevant standard for guidance. This standard is applicable to insulating liquids and used sample containers, the disposal or decontamination of which must be done according to local regulations. Every precaution should be taken to prevent release of mineral oil into the enviro
34、nment. 4 Significance It is well known that particles have a detrimental effect on the dielectric strength of insulating liquids. It has long been the practice to include in specifications of insulating liquids the requirement that the fluid be clear and free of visible particulate matter. However,
35、there has been no standard method for quantitative estimates, so that practices have differed. This standard gives standard procedures for the test. Filtration of insulating liquids is an established practice in the electrical industry. The procedure described may serve to assess the performance of
36、the filter system. The results obtained are dependent upon the method used. With the automatic counter the measured values also depend on the calibration procedure and in particular on the calibration material. It is therefore essential that the methods of analysis and the calibration standards are
37、specified when quoting results. The particle content of a sample may depend on different transformer parameters as well as the condition of the oil itself. Storage may affect the sample, due to sedimentation and/or coalescence of particles. Shaking of the sample before analysis will be necessary. 5
38、Comparison and limitation of the methods Automatic particle counters using the light interruption principle are quick and easy to use, but the following points should be borne in mind: With some liquids it may be necessary to modify their viscosity to comply with the operating parameters of the inst
39、rument. It is necessary to choose a sensor head suitable for counting in the size range required. No single head can count both very small particles (200 m). The instrument records the light interruption area of the particle and from this calculates the diameter of a sphere having the equivalent are
40、a or the longer axis of a specified ellipsoid with the same area, as established by ISO 4407. When measurements are carried out with automatic particle counters, the reported sizes are expressed as m(c) to indicate that the particle size has been calculated from the observed cross-sectional area. Pa
41、rticle sizes from optical microscope counting are expressed as m. The relationship between the two units is described in ISO 4406: 6 m(c) corresponds to 5 m 14 m(c) corresponds to 15 m. Automatic counters give no information as to the shape of the particles, and this constitutes a limitation with re
42、spect to the recognition of fibres. Their narrow and elongated shape results in a slight light obscuration and consequently in a very small equivalent sphere diameter. The results obtained can be different from those obtained by microscope counting. When it is important to evaluate the concentration
43、 of fibres, automatic counters cannot perform this task adequately. When air-saturated or over-saturated liquids are shaken manually or in a shaking machine, or given high-energy ultrasonic treatment, finely dispersed micro-bubbles may be formed 6 BS EN 60970:2007in the liquid. In the optical system
44、 of the automatic counter, these micro-bubbles will be counted as solid particles. These difficulties are avoided when using either of the optical microscopic methods. In addition, optical microscopy may give some information about the types of particles present. These methods are, however, much mor
45、e time-consuming and operator dependent and may be very difficult to count particles of less than 5 m. 6 Types and identification of particles The origins of particles found in insulating liquids are manifold. In new, unenergized, equipment the insulating liquid may contain cellulose fibres plus par
46、ticles from the manufacturing process. These could include iron, aluminium, brass, welding cinder and sandblasting materials. Insulating liquids in working transformers, at both normal and overload temperatures, slowly acquire soot and sludge particles. Localised overheating over 500 C could be a so
47、urce of carbon. The carbon particles produced in the OLTC diverter may migrate by leakage, accidents or human error into the bulk fluid compartment and contaminate the full charge. A typical source of metallic particles is from pump bearing wear, although corrosion and arcing on metallic components
48、may also produce particles. Cellulose lint, sand, dust and particles of varnish, plastic or rubber can also be found in the fluid of transformers in service. A knowledge of which particle types are present in the insulating liquid can, in certain cases, help in assessing the conditions of the equipm
49、ent, in diagnosing a fault or indicating a risk of failure. The most dangerous particles are the conductive ones (metals, carbon, wet fibres, etc.). Particle identification and counting have been found to be necessary procedures of condition monitoring (CIGRE brochures 1571 and 2272). Certain particles may be identified by filtering a sample through a membrane filter and examining the residue under a microscope (EN 50353). At this stage some fibres can be identified usi
