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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The value of its square is between 0 no correlation and 1 complete correlation. It is good practice to prepare additional specimens, or at least to provide a reserve of the original material batch from which such specimens may subsequently be prepared. Further guidance will be found in IEC In such cases it is often convenient to start by loading the ageing oven with one-half of the prepared specimens and performing measurements after the second or third exposure cycle of the recommended series.

Where the derivation is graphical or the statistical conditions are not satisfied the format is as follows: Place one group for exposure in each of the ovens complying with 5.

In the case of destructive tests 6. Diagnostic procedures may be non-destructive or destructive determinations of a property or potentially destructive proof tests see 5. We accept all major credit cards American Express, Mastercard and VisaPayPal and bank transfers as form of payment. However, for some materials very sensitive to the humidity in the ovens, more reliable results are obtained when the absolute humidity in the ageing oven room is controlled and equal to the absolute humidity corresponding to standard atmosphere B according to IEC 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.

The row in table 1 corresponding to the estimated TI shows suggested ageing times in days at oven temperatures which appear at the head of the respective columns.

For the determination of the initial value, see 5. It was subsequently found that the statistical confidence index included in the TEP was not widely understood or used. NOTE 1 It is suggested that individual specimens be identified to simplify their return to the correct oven after each test.

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These further tests may be at lower or intermediate temperatures but should not generally be at higher temperatures than originally selected.

Consequently, a material may be assigned more than one temperature index, derived, for example, from the measurement of different properties and the use of different end-point times. Find out more about British Standards by visiting our website at bsigroup.

The first assumption is tested by the so-called Fisher test F -test.

The cycles of temperature exposure may be continued until all specimens have failed, so that a more complete statistical analysis may be made see IEC Groups are tested as indicated in the table. Ageing at lower temperature s of one or two additional group s of specimens in case of suspected non-linearity can then be initiated immediately to produce the complete test data within a time limit which is still acceptable. Such complications may arise, for example, if the thermal endurance relationship turns out to be non-linear, or if specimens are lost due to thermal runaway of an oven.

A choice of properties is given in IEC This standard is concerned only with type 2. This publication does not purport to include all the necessary provisions of a contract. A flow chart and decision table setting out the procedures and conditions are given in Annexes A and B of IEC For graphical derivation and in some other cases the treatment of data may be simpler if the number of specimens in each group is odd.

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iecc Physico-chemical models postulated for the ageing processes led to the almost universal assumption of the Arrhenius equations to describe the rate of ageing. The y -values derived are used in the calculations of lec. In order to carry out valid calculations, one or more further group s of specimens shall be aged at such a lower temperature as will enable the conditions to be met.

The following dates are fixed: If this rule results in changes of mechanism for example, when a transformation point like melting or softening is exceededthen the maximum exposure temperature will need to be limited. 60261-1 the rest of this standard the term “insulating materials” is always taken to mean “insulating materials and simple combinations of such materials”.

Either a new group, possibly with a shorter cycle time, should be started, or the first cycle failure ignored and the nominal size of the group reduced by one for example, a temperature group of 21 would be treated in the mathematical process as 20; see 6. These tests have been designed to test all important aspects of the data which might invalidate derivation of thermal endurance 60261-1, as well as to decide whether a failure to satisfy the statistical requirements is of practical significance.

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However, the planned number of groups of specimens at each temperature see 5. Although originally developed for use with electrical insulating materials and simple combinations of such materials, the procedures are considered to be of more general applicability and are widely used in the assessment of materials not intended for use as electrical insulation.

Figure 4 — Destructive tests — Estimation of time to end-point 6. After successive delays see footnote in Table B. NOTE The term Arrhenius is widely used and understood to indicate a linear relationship between the logarithm of a time and the reciprocal of the thermodynamic absolute or Kelvin temperature.

About us We bring together business, industry, government, consumers, innovators and others to shape their combined experience 660216-1 expertise into standards -based solutions. It constitutes an editorial revision where the simplified method has been removed and now forms Part 8 of the IEC series: Related publications IEC Some test properties may require measurement at the oven temperature, in which case the ageing is continuous.

To achieve this, select the 602166-1 length so that the mean or median time to end-point is reached in about 10 cycles but not less than seven. BSI is incorporated by Royal Charter. For materials in which a significant variation of properties with temperature or humidity is expected, unless otherwise specified, condition the specimens 602161- in standard atmosphere B of IEC 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.

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