IEC · IEC · IEC · IEC · IEC · IEC ; Show all». IEC Standard | Guide for the determination of thermal endurance properties of ekectrical insulating materials – Part 2: List of. IEC , Electrical insulating materials – Thermal endurance properties – Part 2: Determination of thermal endurance properties of electrical.
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A complicating factor is that the properties of a material subjected to thermal ageing may not all deteriorate at the same rate, and different end-points may be relevant for different applications.
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Ageing ovens – Single-chamber ovens Electrical insulating materials – Thermal endurance properties Part 8: Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.
In the official version, for Bibliography, the following notes have to be added for the standards indicated: The time interval between tests of groups should be planned so that the results of at least two groups of specimens are available before the mean time to end-point, and at least one after: The validity of the model is, therefore, not dependent on the more stringent condition of a linear relationship between the level of the diagnostic property and the degree of molecular change.
This led to the concept of the “Thermal Endurance Profile” TEPincorporating the temperature index, its variation with specified ageing time, and a confidence limit. Licences can cover as few or as many users as you wish. This model is valid when the selected end-point of the diagnostic property is correlated with a particular degree of molecular change in the material which is subject to ageing.
The first assumption is tested by the so-called Fisher test F -test. This value might be selected with respect to usual service requirements. 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. This does not necessarily imply a complete repeat of the experimental work, since it is possible if material is available to test further specimens and add the results to the original data.
If such material specifications are not available, a selection of properties and methods for the evaluation of thermal endurance is given in IEC A choice of properties is given in IEC The size of the confidence interval is roughly proportional to the square root of the reciprocal of the total number of data values.
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IEC () (R) | Standards Council of Canada – Conseil canadien des normes
Together with BS EN The knowledge embodied in our standards has been carefully assembled in a dependable format and refined through our open consultation process. The circulation of the air within the oven and the exchange of the air content should be adequate to ensure that the rate of thermal degradation is not influenced by accumulation of decomposition products or oxygen depletion see 5. In either case, the specimen preparation technique should be carefully examined.
For undated references, the latest edition of the referenced document including any amendments applies. For the valid application of the standard, no transition, in particular no first-order transition should occur in the temperature range under study. This, or other specified conditions, shall then be reported.
In the case of proof tests with incomplete data usually censored at the medianit may be possible to obtain a sufficient increase in data group size by continuing the exposure until further test specimens have failed the proof test.
To find out more about becoming a BSI Subscribing Member and the benefits of membership, please visit bsigroup. It is necessary to ensure that the intercept of the regression line with the time axis gives the same value as the mean of the intercepts of the individual lines.
It is advisable to distinguish between: 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. For non-destructive tests, although Table 1 suggests constant cycle lengths, test times following a geometric series may be used.
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. Failures at the end of the first ageing cycle cannot be accepted. After each removal, allow the group of specimens to cool to room temperature unless otherwise specified.
Standards Council of Canada
These further tests may be at lower or intermediate temperatures but should not generally be at higher temperatures than originally selected. Users are responsible for its correct application. Avenue Marnix 17, B – Brussels?
The following dates are fixed: 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. The value of its square is between 0 no correlation and 1 complete correlation. It is strongly recommended that the full evaluation procedure, as described below and in iiec.
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_百度文库
A simplified calculation procedure is described in IEC Ageing procedures and evaluation of test results IEC NOTE The ageing graph is formed by plotting the value of property or a suitable transform of its value against the logarithm of the exposure time. TC – Evaluation and qualification of electrical insulating materials and 602162- rss.
It was felt to be much more important that assurance could be given that the difference between the calculated TI and its lower confidence limit was less than a specified value.