IEC. Fourth edition. Electrical insulating materials – +41 22 02 11 Telefax: +41 22 03 00 E-mail: [email protected] Web: 标准 IEC 电气绝缘材料 耐热性 第1部分：老化程序和试验结果的 评定_电力/水利_工程科技_专业资料。标准 IEC 电气. this publication, including its validity, is available in the IEC Catalogue of IEC Electrical insulating materials – Properties of thermal endurance.
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In this way, the total amount of testing is reduced, without loss of discrimination. When the criterion is an absolute property level, n d is usually given the value of zero, unless reporting of the initial value is required. This, or other specified conditions, shall then be reported.
Together with BS EN A simplified procedure is given in IEC The abscissa is usually graduated in a non-linear Celsius temperature scale oriented with temperature increasing from left to right. Since processing conditions may significantly affect the ageing characteristics of some materials, it shall be ensured that, for example, sampling, cutting sheet from the supply roll, 602166-1 of anisotropic material 6021-61 a given direction, molding, curing, pre-conditioning, are performed in the same manner for all specimens.
About us We bring together business, industry, government, consumers, innovators and others to shape their combined experience and expertise into standards -based solutions. The reference level may for example, be a mean value one parameter or a line two parameters, slope and intercept.
Ageing procedures and evaluation of test results 1 Scope This part of IEC specifies the general ageing conditions and procedures to be used for deriving thermal endurance characteristics and gives guidance in using the detailed instructions and guidelines in the other parts of the standard.
You can keep in touch with standards developments and receive substantial discounts on the purchase price of standards, both in single copy and subscription format, by becoming a BSI Subscribing Member. These values are intended solely as illustration and may be changed as the work requires. If the results show that this time to end-point is likely to be reached in about 10 periods of exposure, there is no need to alter the period of exposure originally selected.
However, further irc will be found in IEC It is advisable to distinguish between: Figure 4 — Destructive tests — Estimation of time to end-point 6. In addition to the above-mentioned basic assumption, some general assumptions regarding the chemical mechanisms of the thermal ageing need to be satisfied: Particular care will be needed for very short specification times, since the iex ageing temperatures may lead into temperature regions which include transition points, for example, glass transition temperature or partial melting, with consequent non-linearity.
For 660216-1 materials, it is not possible to achieve a time to end-point of less than h while retaining satisfactory linearity. The chosen property should reflect, in a significant fashion if possible, a function of the material in practical use.
This difference is dependent on the scatter of the data points, the deviations from linearity in the regression analysis, the number of data points and the extent of extrapolation.
The degree of degradation indicated as the end-point of the test should be related to the allowable safe value for the material property which is desired ice practice. The method of evaluation of TI results is by the numerical procedure detailed in IEC together with a graphical presentation as shown in Figure 1.
This value might be selected with respect to usual service requirements. It is permitted for these conditions not to be satisfied in specified circumstances either a small extrapolation or linearity test at significance level 0, may be permitted; see 6. The thickness is also important because the rate of ageing may vary with iwc.
NOTE 1 This table is intended primarily for cyclic proof testing and non-destructive tests, but may also be used as a guide for selection of suitable time intervals for destructive tests. This approach will provide comparisons among materials but bears a poorer relationship than item b to the property values required in normal service.
An approximately linear region of the ageing graph is selected Figure 3 and a line parallel to the mean ageing graph drawn through each time, property point. Except as permitted under the Copyright, Designs and Patents Act no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means — electronic, photocopying, recording or otherwise — without prior written permission from BSI.
Determination of thermal endurance properties of electrical insulating materials — Choice of test criteria IEC IECStandard conditions for use prior to and during the testing of solid electrical insulating materials IECElectrical insulating materials — Thermal endurance properties — Part 2: This procedure is based on the assumption that the ageing rate of all specimens aged at one temperature is the same and can therefore be determined from the ageing rate of the property means of the successive groups tested.
However, it is important that a smaller range of mean times to end-point will lead to a larger confidence interval of the result for the same data dispersion. Ageing data of materials with different thicknesses are not always comparable.
In the official version, for Bibliography, the following notes have to be added for the standards indicated: However, there is often a need for such information related to other longer or shorter times. Simultaneously with the development of the IEC series, other standards were being developed in ISO, intended to satisfy a similar requirement for plastics and rubber materials.
Unless otherwise stated in the method for determining the diagnostic property for example, parts of material specifications dealing with methods of test, or a method listed in IECthe initial value is the arithmetic mean of the test results. There are two alternative ways in which the end-point may be defined: In obtaining the RTI, the systematic errors observed in the determination of TI are to a large extent compensated.
However, environmental conditioning, the influence of atmospheres other than air and immersion in liquids such as oil may be important, but these are not the concern of this standard. Divide the specimens by random selection into as many groups as there are exposure temperatures. The material specifications or the test standards will contain all necessary instructions for the preparation of specimens.
From these values, if necessary by interpolation see Figure 2obtain the time to end-point and calculate its logarithm as the y -value to be used in 6.