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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This sixth edition cancels and replaces the fifth edition, published in 6021-1 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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Determination of thermal endurance properties of electrical insulating materials Choice of test criteria Electrical insulating materials – Thermal endurance properties Part 3: It was subsequently found that the statistical confidence index included in the TEP was not widely understood or used.
Table 1 gives guidance in making initial selections. Where the test criterion for non-destructive or proof tests is based upon the initial value of the property, this should be determined from a group of specimens of at least twice the number of specimens in each temperature group. Figure 4 — Destructive tests — Estimation of time to end-point 6. 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.
Instructions for calculating thermal endurance characteristics using simplified procedures 1 1 ———————— To be published. BSI is incorporated by Royal Charter. Prepare a number of specimens following the instructions in 5. Kec 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.
This model is iiec 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.
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Users are responsible for its correct application. In obtaining the RTI, the systematic errors observed in the determination of TI are to a large extent compensated.
This led to the concept of the “Thermal Endurance Profile” TEPincorporating the temperature index, its variation with specified ageing time, and a confidence limit. If these expedients are not successful, it will be necessary to test at a temperature low enough for extrapolation not to be required.
In the application of this standard, it is assumed that a practically linear relationship exists between the logarithm of the time required to cause the predetermined property change and the reciprocal of the corresponding absolute temperature Arrhenius relationship.
After each removal, allow the group of specimens to cool to room temperature unless otherwise specified. If the data dispersion is not high through inadequate experimental technique, the effect of the high dispersion can be overcome by the use of a larger number of data values, i. These may be briefly expressed as follows see 3. Generally, the following instructions 5.
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Organizations of all sizes and across all sectors choose standards to help them achieve their goals. Unless otherwise specified, IEC shall apply.
TEP was then abandoned, with the TI and HIC being reported iecc a way which indicated whether or not the statistical tests had been fully satisfied. There are two alternative ways in which 6026-1 end-point may be defined: In the official version, for Bibliography, the following notes have to be added for the standards indicated: Where the derivation is graphical or the statistical conditions are not satisfied the format is as follows: Five of the test groups are placed in the oven at the beginning of the sequence.
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. In cases of longer times, for example, the times given as requirements or recommendations in the text of this standard for example, 5 h for the minimum value 60216- the longest time to end-point shall be increased in the ratio of the actual specification time to 20 h. Instructions for calculating thermal endurance characteristics IEC all Parts 4Iev insulating materials — Thermal endurance properties — Part 4: A simplified procedure is given in IEC Consequently, a material may be assigned more than one thermal endurance characteristic derived from the measurement of properties at different thicknesses.
Together with BS EN 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 6021-61 to be met. Find out more about British Standards by visiting our website at bsigroup.
Note 2 to entry: This edition constitutes an editorial revision where the simplified method has ifc removed and now forms Part 8 of the EN Series: Ageing data of materials with different thicknesses are not always comparable. Such complications may 6021-1, 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.
This standard is concerned only with type 2. 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.
Since processing conditions may significantly affect the ageing characteristics of some materials, it shall iex ensured that, for example, sampling, cutting sheet from the supply roll, cutting of anisotropic material in a given direction, molding, curing, pre-conditioning, are performed in the same manner for all specimens. For the valid application of lec standard, no transition, in particular no first-order transition should occur in the temperature range under study.
The parameters are referred to as the regression coefficients. NOTE 2 The above definition is not strictly compatible with the figure and also differs slightly ief the definition in the second edition of IEC Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.
In either case, the specimen preparation technique should be carefully examined. To provide uniform conditions, the conditioning of specimens after removal from the oven and before measurement may need to be specified. The IEC series has been developed to formalize these procedures and the interpretation of their results. Relevant and detailed instructions on how to proceed using non-destructive, proof or destructive test criteria are provided in 5.
If the results do not show this, the period may be changed so that the median result may be expected in at least seven cycles preferably about 10 provided this change in cycle time is made before the fourth cycle. 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.