1、BRITISH STANDARD BS EN 61621:1998 IEC 61621: 1997 Dry, solid insulating materials Resistance test to high-voltage, low-current arc discharges The European Standard EN 61621:1997 has the status of a British Standard ICS 29.035.01BSEN 61621:1998 This British Standard, having been prepared under the di
2、rectionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15 February 1998 BSI 05-1999 ISBN 0 580 29017 4 National foreword This British Standard is the English language version of EN 61621:1997. It is identical with IEC 61621:1997.
3、The UK participation in its preparation was entrusted by Technical Committee GEL/15, Insulating materials, to Subcommittee GEL/15/5, Methods of test, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on th
4、e interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. From 1 January 1997, all IEC pub
5、lications have the number 60000 added to the old number. For instance, IEC 27-1 has been renumbered as IEC60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. Cross-references Attention is drawn to the fa
6、ct that CEN and CENELEC Standards normally include an annex which lists normative references to international publications with their corresponding European publications. The British Standards which implement these international or European publications may be found in the BSI Standards Catalogue un
7、der the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct
8、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 front cover, pages i and ii, theEN title page, pages 2 to 10 and a back cover. This standard has been updated (see copyright da
9、te) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSEN 61621:1998 BSI 05-1999 i Contents Page National foreword Inside front cover Foreword 2 Text of EN 61621 3ii blankEUROP
10、EAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 61621 November 1997 ICS 29.035.01 Descriptors: Insulation, electrical insulation, electrical resistance, insulation resistance, electrical tests, impulse-voltage tests, electricdischarges, electric arcs, high voltage tests, low voltage, tests English v
11、ersion Dry, solid insulating materials Resistance test to high-voltage, low-current arc discharges (IEC61621:1997) Matriaux isolants solides secs Essai de rsistance aux dcharges larc haute tension, faible courant (CEI 61621:1997) Trockene, feste Isolierstoffe Prfung der Lichtbogenbestndigkeit bei ho
12、her Spannung und niedrigem Strom (IEC 61621:1997) This European Standard was approved by CENELEC on 1997-10-01. 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
13、 alteration. Up-to-date lists and bibliographical references concerning such national standards 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
14、 by translation under the responsibility of a CENELEC member into its own language and notified 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
15、, Greece, Iceland, Ireland, Italy, Luxembourg, 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 Central Secret
16、ariat: rue de Stassart 35, B-1050 Brussels 1997 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61621:1997 EEN 61621:1997 BSI 05-1999 2 Foreword The text of document 15E/56/FDIS, future edition 1 of IEC 61621, prepared by SC 15E, Me
17、thods of test, of IEC TC 15, Insulating materials, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61621 on 1997-10-01. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard, Annex ZA is normative. Annex
18、 ZA has been added by CENELEC. Endorsement notice The text of the International Standard IEC 61621:1997 was approved by CENELEC as a European Standard without any modification. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Apparatus 3 4.1 Test circuit 3 4.2 Electrodes
19、 and electrode assembly 4 4.3 Test chamber 5 4.4 Calibration 5 5 Specimens 5 6 Conditioning 5 7 Procedure 5 8 Results 5 9 Report 6 Annex ZA (normative) Normative references to international publicationswiththeir corresponding Europeanpublications 10 Figure 1 Example for electrical circuit 7 Figure 2
20、 Electrode mounted in a shank (example) 8 Figure 3 Electrode assembly (example) 9 Table 1 Sequence of 1min steps 6 latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 1998-07-01 latest date by which the national
21、 standards conflicting with the EN have to be withdrawn (dow) 1998-07-01EN 61621:1997 BSI 05-1999 3 1 Scope This International Standard describes a test method which can provide preliminary differentiation between similar insulating materials, with respect to their resistance to damage when exposed
22、to high-voltage, low-current arc discharges, occurring close to their surfaces. The discharges cause localized thermal and chemical decomposition and erosion and eventually a conductive path forms across the insulating material. The severity of the test conditions is gradually increased: in the earl
23、y stages a low-current arc discharge is repeatedly interrupted, whereas in the later stages, the arc current is raised in successive steps. Because of its convenience and because of the short time required for testing, the test method is applicable for preliminary screening of materials, for detecti
24、ng the effects of changes in formulation and for quality control testing. Previous experience with this test, showed acceptable reproducibility with thermoset materials. Using thermoplastics, some testing laboratories report unacceptably large variation in test results which lead to the recommendati
25、on not to use the test for thermoplastics. NOTEAttempts are being made to reduce the variability of the results of tests on thermoplastics by controlling the electrode pressure and depth of penetration into the material during the test. Without such electrode control, tests on many thermoplastics ma
26、y not be sufficiently meaningful to be performed. This test method will not, in general, permit conclusions to be drawn concerning the relative arc resistance rankings of materials which may be subjected to other types of arcs. The ranking of materials may differ from that found in wet tracking test
27、s (e.g. IEC 60112, IEC 60587 and IEC 61302) and from their performance in service, where the intensity, recurrence frequency and time of exposure to arc discharges are very different. 2 Normative references The following normative documents contain provisions, which through reference in this text, c
28、onstitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recen
29、t editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 60112:1979, Method for determining the comparative and the proof tracking indices of solid insulating materials under moist conditions. IEC 60212:1971, Sta
30、ndard conditions for use prior to and during the testing of solid electrical insulating materials. IEC 60587:1984, Test methods for evaluating resistance to tracking and erosion of electrical insulating materials used under severe ambient conditions. IEC 61302:1995, Electrical insulating materials M
31、ethod to evaluate the resistance to tracking and erosion Rotating wheel dip test. 3 Definitions For the purpose of this International Standard, the following definitions apply: 3.1 failure failure is considered to have occurred when a conducting path is formed in the material; failure is also consid
32、ered to have occurred if the arc causes a material to burn and the burning continues when the arc is interrupted NOTE 1When the arc disappears into the material, the circuit current usually changes and a noticeable change in sound takes place. NOTE 2For some materials, the trend towards failure incr
33、eases over a fairly long interval of time before all parts of the arc between the electrodes have disappeared. Failure only occurs when the entire arc has disappeared. NOTE 3For some materials, a persistent scintillation may be observed close to the electrodes after the arc has disappeared. This sci
34、ntillation shall not be considered as part of the arc. NOTE 4Burning of the material accompanying the arc is only considered as failure if the burning continues between arc interruptions. Otherwise the test is continued until a conducting path is formed. NOTE 5The first disappearance of the entire a
35、rc is considered as failure even if the material recovers for subsequent arcing. 3.2 arc resistance total time in seconds from the start of test until specimen failure 4 Apparatus 4.1 Test circuit The principal components of the electrical circuit for the apparatus are shown in Figure 1. NOTEIn the
36、secondary circuit wiring the stray capacitance should be less than 40 pF. Large stray capacitance may disturb the arc shape and influence the test results. 4.1.1 Transformer, T v A transformer with a rated secondary potential (on open circuit) of 15 kV, and a rated secondary current (on short circui
37、t) of 60 mA, line frequency (48 Hz to62 Hz).EN 61621:1997 4 BSI 05-1999 4.1.2 Variable autotransformer, T c Rated 1 kVA and suitable for the line voltage. NOTEA constant primary voltage supply 2 % is recommended. 4.1.3 Voltmeter, V L AC voltmeter with an accuracy of 0,5 % capable of reading line vol
38、tage %. 4.1.4 Milliammeter, A A true r.m.s. a.c. milliammeter capable of reading10mA to 40 mA with an accuracy of 5 %. Since this milliammeter is used only when setting up or making changes in the circuit, it may be shorted out by a bypass switch when not in use. NOTEAlthough provision has been made
39、 for the suppression of radio frequency components of current in the arc, it may be desirable to check for their presence when the apparatus is first constructed. This is best done by use of a suitable thermocouple type r.f. milliammeter temporarily inserted in series with the milliammeter. 4.1.5 Cu
40、rrent control resistors, R 10 , R 20 , R 30and R 40 Four resistors are required in series with the primary of T v . These resistors must be adjustable, to some extent, to permit exact settings of the currents during calibration. R 10is always in the circuit to provide a 10 mA current. 4.1.6 Suppress
41、ing resistor, R 3 Rated at 15 k7 1,5 k7 and at least 24 W. This resistor, along with the inductors (see 4.1.7) is used to suppress parasitic high frequency in the arc circuit. 4.1.7 Air core inductors, X s , 1,2 H to 1,5 H NOTEA single coil of this inductance is not practical. A satisfactory inducto
42、r may be constructed by connecting in series eight coils of 3000 to 5000 turns of wire wound on insulating non-metallic cores of about 12,7mm diameter and 15,9mm inside length. 4.1.8 Breaker, B Motor driven or electronically operated interrupter used to give the required cycles for the three lower s
43、teps of the test by opening and closing the primary circuit according to the schedule in Table 1, with an accuracy of 0,008s. 4.1.9 Timer, TT A stop watch or electric interval timer accurate to1s. 4.1.10 Contactor C s When the draft shield, enclosing the electrode assembly, is in lowered position, i
44、t actuates a normally open (NO) microswitch which, in turn, operates contactor C sand connects the transformer T vto the circuit, allowing application of HV to the electrodes. With the draft shield raised, the transformer is disconnected and the operator is protected. 4.2 Electrodes and electrode as
45、sembly 4.2.1 Electrodes The electrodes are made from 2,4mm 0,05mm diameter tungsten rod which is free from cracks, pits or rough spots. The free electrode length shall be a minimum of 20mm. It is recommended that the electrodes are mounted in a shank which allows correct orientation of the electrode
46、 tip after sharpening. The electrode tip shall be ground and polished to produce an angle of 30 1 to the axis, to achieve a flat elliptical face. As an example, Figure 2 shows the electrodes mounted in a suitable shank. NOTE 1Tungsten welding rods have been found to be suitable for use as electrodes
47、. NOTE 2A steel jig for securing the electrodes during sharpening to ensure finishing the pointed tips to the proper geometry is helpful. 4.2.2 Electrode assembly This assembly provides a means of holding the electrodes and the test specimen at the proper angle for applying the arc to the top surfac
48、e of the test specimen. It shall be constructed so that the top surface of each specimen is at the same height for each test. Each electrode shall be adjusted so that it rests independently on the test specimen with a force of 0,5N 0,05N. The test specimen shall be protected from air drafts, and sha
49、ll be allowed venting of combustion products in cases where test specimens give off smoke or gases during the test. The electrodes shall be positioned so that when they are resting on a test specimen, they lie in the same vertical plane and are both inclined 35 1 from the horizontal (thus the angle between the axis of the electrodes is 110 2 ), as shown in Figure 3. The minor axes of the elliptical tip surfaces shall be horizontal with the spacing of the tips adjusted to6,35mm 0,1mm. A clear view shall be provided of
