BS-7836-1996 IEC-60450-1974.pdf
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1、BRITISH STANDARD BS 7836:1996 IEC 450:1974 Measurement of the average viscometric degree of polymerization of new and aged electric papers Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:03 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7836:1996 This Briti
2、sh Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 January 1996 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference GEL/15 Draft
3、 announced in BSI News April 1995 ISBN 0 580 25011 3 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GEL/15, Insulating materials, upon which the following bodies were represented: British Ceramic Research Ltd. British In
4、dustrial Ceramic Manufacturers Association Electrical and Electronic Insulation Association (BEAMA Ltd.) Electricity Association Federation of the Electronics Industry Rotating Electrical Machines Association (BEAMA Ltd.) Transmission and Distribution Association (BEAMA Ltd.) Amendments issued since
5、 publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:03 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7836:1996 BSI 11-1999i Contents Page Committees responsibleInside front cover National forewordii Introduction1 1Object of sp
6、ecification1 2Field of application1 3Principle1 4Cupriethylene-diamine solution2 5Apparatus2 6Preparation of paper sample2 7Experimental procedure2 8Calculations4 9Validity of results4 10Test report5 Appendix A Preparation of the cupriethylene-diamine solution6 Appendix B Checking the ratio cED/cCu
7、of the cupriethylene-diamine solution7 Appendix C8 Appendix D Example of distribution of the values of the degree of polymerization of new papers intended for the insulation of transformers9 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:03 GMT+00:00 2006
8、, Uncontrolled Copy, (c) BSI BS 7836:1996 ii BSI 11-1999 National foreword This British Standard has been prepared by Technical Committee GEL/15. It is identical with IEC 450:1974 Measurement of the average viscometric degree of polymerization of new and aged electrical papers, published by the Inte
9、rnational Electrotechnical Commission (IEC). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligatio
10、ns. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 9 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. Lic
11、ensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:03 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7836:1996 BSI 11-19991 Introduction This specification has been prepared as the result of work carried out by the Working Group “Paper-Oil” of C.I.G.R.E. Study Co
12、mmittee “Insulating Oils”. It is based on the experimental procedure described in the French Specification AFNOR NF T 12 005. To obtain values of the degree of polymerization which are reproducible in different laboratories, the requirements of the present test procedure shall be observed in all res
13、pects. However, it may be found that the sample is not satisfactorily dissolved after the preferred solution time of 2 h, in such a case this time may be increased up to a maximum of 18 h. For a sample of aged paper, there is little risk that this increase of solution time will cause further signifi
14、cant degradation. 1 Object of specification This specification describes a standard method for determining the average viscometric degree of polymerization (abbreviated ) of new or aged electrical papers. The determination is made by measuring the intrinsic viscosity of a solution of the paper in an
15、 appropriate solvent. The degree of polymerization (or the degree of condensation) of a particular cellulose molecule is the number of anhydrous-glucose monomers, C6H10O5, in the cellulose molecule. Within a sample of paper, all the cellulose molecules do not have the same degree of polymerization s
16、o that the mean value measured by viscometric methods is not necessarily the same as that which may be obtained by, for instance, osmotic or ultracentrifuging methods. 2 Field of application This specification may be applied to all papers made from “pure” (unmodified) cellulose, as used in transform
17、er, cable or capacitor manufacture. It applies to new or aged papers. For information, Appendix D shows an example of statistical distribution of DPv values for new papers intended for the insulation of transformers, together with information relative to cable and capacitor papers. Nevertheless, whe
18、re evaluating the decomposition stage of aged papers, care should always be taken to use, as a reference, the DPv value of a new paper of the very same origin, DPv of new papers being a function of their specific gravity and of their manufacturing process. The methods described can also be used for
19、the determination of the intrinsic viscosity of solutions of chemically modified papers, provided that these dissolve completely in the selected solvent. The method described shall be used with caution when it is applied to loaded papers. 3 Principle The method used is to measure the specific viscos
20、ity1) of a solution of the paper in cupriethylene-diamine. From this measurement the intrinsic viscosity of the solution is deduced, and from this the degree of polymerization is easily calculated. The specific viscosity s is defined by: The intrinsic viscosity is defined by: where c is the concentr
21、ation of the solution. The average viscometric degree of polymerization(the ratio of the mean molecular mass indicated viscometrically to the molecular mass of the monomeric unit is related to the intrinsic viscosity by the equation: K and being characteristic coefficients of the polymer-solvent sys
22、tem (paper, cupriethylene diamine) and of the monomer. The intrinsic viscosity is calculated from the specific viscosity s and the concentration c by Martins empirical formula: DPv 1) Solutions of cellulose are non-Newtonian fluids (their viscosity decreases as the flow velocity increases sometimes
23、known as “structural viscosity”). Although the viscosity of dilute solutions varies only slightly with the gradient of the velocity modulus, it is necessary to comply strictly with the conditions laid down in this specification to ensure maximum accuracy (the gradient of the velocity modulus shall n
24、ot exceed 300 to 500 s1). s viscosity of paper solutionviscosity of solvent viscosity of solvent - -= DPv Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:57:03 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7836:1996 2 BSI 11-1999 4 Cupriethylene-diamine solut
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