1、 ISO 2012 Rubber, vulcanized or thermoplastic Determination of insulation resistance Caoutchouc vulcanis ou thermoplastique Dtermination de la rsistance disolement INTERNATIONAL STANDARD ISO 2951 Second edition 2012-06-01 Reference number ISO 2951:2012(E) ISO 2951:2012(E) ii ISO 2012 All rights rese
2、rved COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the addr
3、ess below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ISO 2951:2012(E) ISO 2012 All rights reserved iii Contents Page Foreword
4、 iv Introduction v 1 Scope 1 2 Normative references . 1 3 T erms and definitions . 1 4 Test equipment . 1 5 Electrodes . 1 5.1 General . 1 5.2 Conducting-paint electrodes (for flat plates, tubes and rods) 2 5.3 Bar electrodes (for thin sheets and tapes) . 2 6 Test pieces 2 6.1 Test pieces for conduc
5、ting-paint electrodes . 2 6.2 Test pieces for bar electrodes 2 6.3 Attachment of electrodes 2 6.4 Conditioning . 2 6.5 Number of test pieces 2 7 Procedure 3 8 Expression of results . 3 8.1 Test pieces using conducting-paint electrodes 3 8.2 Test pieces using bar electrodes 3 9 Test report . 3 Annex
6、A (informative) Cleaning and mounting of test pieces 7 Bibliography . 8 ISO 2951:2012(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out
7、 through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO col
8、laborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International S
9、tandards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements
10、 of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 2951 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis. This second edition cancels and replace
11、s the first edition (ISO 2951:1974), which has been technically revised as follows: the title and scope have been modified to include thermoplastic rubbers; the normative references have been updated; the instructions in old subclause 6.2 (now 5.3) concerning rigid materials have been deleted; the n
12、umber of test pieces tested is now “more than three” (see 6.5), as opposed to “three” in the previous edition; the test report has been updated. iv ISO 2012 All rights reserved ISO 2951:2012(E) Introduction This International Standard specifies an empirical method that gives a value for insulation r
13、esistance which includes, without discrimination, both volume and surface resistance. This value can be used for the comparison of the quality of different insulating rubbers. For general principles regarding measuring resistance, general effects of temperature and humidity, applied voltage and time
14、 of electrification, see IEC 60093 and IEC 60167 3 . ISO 2012 All rights reserved v Rubber, vulcanized or thermoplastic Determination of insulation resistance 1 Scope This International Standard specifies a method for the determination of the insulation resistance of vulcanized and thermoplastic rub
15、bers without discrimination between the volume and surface resistances involved. This method should only be used for test pieces with a resistance greater than 10 8. NOTE Methods of test for test pieces with a lower resistance are described in ISO 1853 and ISO 2878. Because the test pieces are simpl
16、y and easily prepared, this method is particularly useful for rapidly determining values which will give a general indication of quality when great accuracy is not required. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated re
17、ferences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60093, Methods of test for volume resistivity and surface resistivity of solid electrical insulating materials 3 T erms and definitio ns For the pur
18、poses of this document, the following terms and definitions apply. 3.1 insulation resistanceratio of the direct voltage applied to the electrodes to the total current between them at a given time after the application of that voltage NOTE It is dependent upon both the volume and surface resistances
19、of the test piece and is a function of the shape of the test piece. 4 Test equipment The insulation resistance shall be determined either by a bridge method or by measuring the current and voltage. Brief descriptions of suitable equipment are given in IEC 60093. Suitable equipment shall be provided
20、to supply a voltage of (500 10) V d.c., which is steady enough so that the charging current appearing when the voltage varies is negligible compared with the current flowing through the test piece. 5 Electrodes 5.1 General The electrodes shall be made of such a material that they will not corrode un
21、der the conditions of test or react with the material being tested. Suitable electrodes are described in 5.2 and 5.3. INTERNATIONAL STANDARD ISO 2951:2012(E) ISO 2012 All rights reserved 1 ISO 2951:2012(E) 5.2 Conducting-paint el ectrodes (for flat plates, tubes and rods) Conducting paint such as co
22、nductive silver or colloidal graphite with a surface resistance of less than 100 may be used as an electrode material. The liquid phase of the conducting paint shall be of such a nature that it will not have any effect on the insulation resistance to be measured. Apply two equidistant strips of cond
23、ucting paint approximately 1 mm wide around tubes and rods so that the nearest edges are (10 0,5) mm apart. NOTE This can be easily done by mounting the tube or rod in a lathe and rotating it against a small brush or drawing pen containing the paint. This type of electrode may also be used on plate
24、test pieces. In this case, the electrodes shall be two parallel strips of conducting paint approximately 1 mm wide spaced (10 0,5) mm apart, the total length of each electrode being (100 1) mm. Figures 1 and 2 illustrate this type of electrode. 5.3 Bar electrodes (for thin sheets and tapes) Metal ba
25、r clamps measuring about 10 mm 10 mm 50 mm which are spaced (25 0,5) mm apart (see Figure 3) are suitable electrodes for thin sheet material (usually 1 mm or less in thickness) and for flexible tapes. The bar electrodes shall be mounted by means of insulating parts on a metal support to be used as a
26、 guard in the measurement of resistance see Figure 3 a). Alternatively, the electrodes may be supported by the test piece or their connections to the insulated terminals see Figure 3 b). 6 Test pieces 6.1 Test pieces for conducting-paint electrodes For measurements with conducting-paint electrodes,
27、the test pieces shall be rectangular sheets having a size of at least 60 mm 150 mm (see Figure 1), or rods or tubes at least 60 mm long (see Figure 2). 6.2 Test pieces for bar electrodes For measurements with bar electrodes, the test pieces in the form of tapes or thin sheets shall be 26 mm or less
28、in width and at least 50 mm long see Figures 3 a) and 3 b). 6.3 Attachment of electrodes The electrodes shall be attached to the test pieces before conditioning. 6.4 Conditioning Prior to the test, the test piece shall be conditioned, avoiding the application of any stress or strain by bending, twis
29、ting or compression, for at least 16 h at (23 2) C and (50 5) % relative humidity or (27 2) C and (65 5) % relative humidity. The same temperature and humidity shall be used throughout any one test or series of tests intended to be comparable. 6.5 Number of test pieces At least three test pieces sha
30、ll be used. 2 ISO 2012 All rights reserved ISO 2951:2012(E) 7 Procedure 7.1 If necessary, clean the test piece (see Clause A.1 for guidance) and mount it (see Clause A.2 for guidance). Measure the resistance of each test piece individually. The measurement shall be made while the test piece is still
31、 in the conditioning atmosphere. 7.2 Measure the resistance with suitable equipment (see Clause 4) having the required sensitivity and an accuracy of 5 %. Unless otherwise specified, the applied voltage shall be (500 10) V, and the time of electrification 1 min (see IEC 60093). 8 Expression of resul
32、ts 8.1 Test pieces using conducting-paint electrodes The insulation resistance, R 100 , for a standard 100 mm electrode length is calculated using the formula R L R 100 100 = x where R xis the measured insulation resistance, in megaohms; L is the measured length of the electrode, in millimetres. 8.2
33、 Test pieces using bar electrodes The insulation resistance, R 25 , for a standard 25 mm electrode length is calculated using the formula R W R 25 25 = x where R xis the measured insulation resistance, in megaohms; W is the measured width of the test piece, in millimetres. 9 Test report The test rep
34、ort shall include the following information: a) sample details: 1) a full description of the sample and its origin, 2) the method of preparation of the test pieces from the sample, for example moulded or cut; b) test method: 1) a full reference to the test method used, i.e. the number of this Intern
35、ational Standard, 2) the type of test piece used; c) test details: 1) the laboratory temperature and humidity, 2) the number of test pieces used, ISO 2012 All rights reserved 3 ISO 2951:2012(E) 3) the time, temperature and humidity of conditioning prior to the test, 4) the type of electrode used, in
36、cluding the nature of the conducting paint, if used, 5) details of any test piece cleaning procedure used, 6) the test voltage, 7) the time of electrification, 8) details of any procedure not specified in this International Standard; d) test results: 1) the individual test results (i.e. R 100or R 25
37、values), in megaohms, 2) the median value of the insulation resistance, in megaohms; e) the date(s) of the test. 4 ISO 2012 All rights reserved ISO 2951:2012(E) Dimensions in millimetres 1 Key 1 conducting-paint electrodes (approximately 1 mm wide) Figure 1 Plate test piece with conducting-paint ele
38、ctrodes Dimensions in millimetres 1 Key 1 conducting-paint electrodes (approximately 1 mm wide) Figure 2 Tube or rod test piece with conducting-paint electrodes ISO 2012 All rights reserved 5 ISO 2951:2012(E) Dimensions in millimetres 1 22 33 4 4 5 a) 1 4 b) Key 1 metal electrodes 2 metal support an
39、d guard 3 insulating material 4 test piece 5 nuts Figure 3 Bar electrodes for tapes or thin sheet material 6 ISO 2012 All rights reserved ISO 2951:2012(E) Annex A (informative) Cleaning and mounting of test pieces A.1 Cleaning In many cases, it is desirable to test the material in the condition in w
40、hich it is to be used after handling and processing. ln this event, the test pieces should not be cleaned. If cleaning is desired, the surfaces of the test pieces should be cleaned before conditioning with an alcohol and ether mixture or other suitable solvent which does not materially affect the re
41、sistance of the rubber and, thereafter, the surfaces should not be handled with bare fingers (acetate rayon gloves are recommended). A.2 Mounting In mounting the test pieces for measurement, it is important that there be no conducting path between the electrodes other than those associated with the
42、test piece. The supporting material should have a resistance greater than 10 12. When the mounting supports require guarding, this should be done in accordance with the principles given in IEC 60093. ISO 2012 All rights reserved 7 ISO 2951:2012(E) Bibliography 1 ISO 1853, Conducting and dissipative
43、rubbers, vulcanized or thermoplastic Measurement of resistivity 2 ISO 2878, Rubber, vulcanized or thermoplastic Antistatic and conductive products Determination of electrical resistance 3 IEC 60167, Methods of test for the determination of the insulation resistance of solid insulating materials 8 ISO 2012 All rights reservedISO 2951:2012(E) ISO 2012 All rights reserved ICS 83.060 Price based on 8 pages
