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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Instructions for calculating thermal endurance characteristics using simplified procedures. 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. This 06216-1 to the concept of the “Thermal Endurance Profile” TEPincorporating the temperature index, its variation with specified ageing time, and a confidence limit. A number of recommendations and suggestions, useful in establishing times and temperatures, will be found in Annex B.

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. Ifc 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 of the longest time to end-point shall be increased in the ratio of the actual specification time to 20 h.

In the same way, the ageing cycle durations should be changed in approximately the same ratio. The correct usage is restricted to such a relationship between a reaction rate constant and the thermodynamic temperature.

To provide uniform conditions, the conditioning of specimens after removal from the oven and before measurement may need to be specified.

Particular care will be needed for very short specification times, since the higher ageing temperatures may lead into temperature regions which include transition points, for example, glass transition temperature or partial melting, with consequent non-linearity. The temperature extrapolation again shall not exceed 25 K.

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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. Times to end-point, x – and y -values General 6. The end-point should be selected to indicate a degree of deterioration of the insulating material which has reduced its ability to withstand a stress encountered in actual service in an insulation system. 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.

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For some materials, it is not possible to achieve a time to end-point of less than h while retaining satisfactory linearity. These may be briefly expressed as follows see 3. 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. The size of 602166-1 confidence interval is roughly proportional to the square root of the reciprocal of the total number of data values.

A flow chart and decision table setting out the procedures and conditions are given in Annexes A and B of IEC Instructions for an adequate number of specimens are given in IEC This edition constitutes an editorial revision where the simplified method has been removed and now forms Part 8 of the EN Series: A complicating factor is that the properties of a material subjected to thermal 602161- may not all deteriorate at the same rate, 660216-1 different end-points may be relevant for different applications.

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, cutting of anisotropic material in a given direction, molding, curing, pre-conditioning, are performed in the same manner for all specimens.

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There are two alternative ways in which the end-point may be defined: From these values, if necessary by interpolation see Figure 2obtain the time to end-point and calculate its logarithm as the lec -value to be used in 6. 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.

Where the derivation is by the simplified procedure see IEC the format is: The regression analysis for slope and intercept of the thermal endurance graph and the tests for deviations from linearity shall be as in 6. In the case of destructive tests 6.

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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 iex change. General procedures for the determination of thermal endurance properties, temperature indices and thermal endurance profiles withdrawn ISOPlastics — Standard idc for conditioning and testing ISO The analysis of TI data is based on the assumption that there is a linear relation between the logarithm of the time to end-point and the reciprocal of the thermodynamic ageing temperature.

NOTE 2 Attention should be given to the recommendation in 5. Calculation procedures and suitable restrictions have been developed to meet these circumstances and are given in detail in IEC The first assumption is tested by the so-called Fisher test F -test. Instructions for calculating thermal endurance characteristics using simplified procedures Guide for the statistical analysis of ageing test data Part 1: This approach will provide comparisons among materials but bears a poorer relationship than item b to the property values required in normal service.

This standard is concerned only with type 2. Ascending order in this standard implies that the data is ordered in this way, the first orderstatistic being the smallest. Generally, the following instructions 5.

If a time different from 20 h has been used for deriving the TI, the relevant time expressed in kh shall be stated, followed by kh. If end-point is reached in one of the Groups B — F, Groups G — I are immediately removed from the oven and tested after conditioning.

Preview Abstract IEC Throughout the rest of this standard the term “insulating materials” is always taken to isc “insulating materials and simple combinations of such materials”. The common usage is employed throughout this standard. It is strongly recommended that the full evaluation procedure, as described below and in 5.