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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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. 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 Ageing procedures and evaluation of test results IEC The first assumption is tested by the so-called Fisher test F -test.
Return specimens which have withstood the proof test to the oven from which they came, at the same temperature as before, and expose for a further cycle.
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In this test, a test parameter F is calculated from the experimental data and compared with a tabulated value F 0.
Prepare a number of specimens following the instructions in 5. The application of conventional statistical tests, as set out in IECfulfilled this requirement, resulting in the “confidence limit”, TC of TI, but the simple, single-point TI was found inadequate to describe the capabilities of materials.
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 of the longest time to end-point shall be increased in the ratio of the actual specification time to 20 h. 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.
Establish the exposure temperatures and times in accordance with the instructions of 5. These tests have been designed to test all important aspects of the data which might invalidate derivation of thermal endurance characteristics, as well as to decide whether a failure to satisfy the statistical requirements is of practical significance.
On the same graph, plot the ageing temperatures, the times to end-point measured or hypotheticaland the mean times. The correct usage is restricted to such a relationship between a reaction rate constant and the thermodynamic temperature. 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.
If such information is not available, preliminary screening tests may be performed to produce a forecast of the value of TI. A flow chart and decision table setting 600216-1 the procedures and conditions are given in Annexes A and B of IEC Ageing data of materials with different thicknesses are not always comparable. If the results show that this time to end-point is likely to be reached in ic 10 periods of exposure, there is no need to alter the period of exposure originally selected.
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These values are intended solely as illustration and may be changed as the work requires. The size of the confidence interval is roughly proportional to the square root of the reciprocal of the total number of data values.
NOTE 2 Attention should be given to the recommendation in 5. Instructions for calculating thermal endurance characteristics using simplified procedures. A time to end-point within the first ageing period shall be treated as invalid.
If, for example, Group C has reached end-point nine cyclesGroups G, H and I would have received respectively six, seven and eight 6021-1 at testing. Groups are tested as indicated in the table.
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.
Diagnostic procedures may be non-destructive or destructive determinations of a property or potentially destructive proof tests see 5. Instructions for calculating thermal endurance characteristics using simplified procedures Guide for the statistical analysis of ageing test data Part 1: It is advisable to distinguish between: Methods based on mean values of normally distributed test results 3 3.
This will have the effect of decreasing the extrapolation, which is one of the influences in determining the size of the confidence interval, and also make the errors associated with the non-linearity less serious. To reduce the uncertainties in calculating the appropriate thermal endurance characteristic, the overall temperature range of thermal exposure needs to be carefully selected, observing the following requirements if the required thermal endurance characteristics are for a projected duration of 20 Instructions for 6026-1 adequate number of specimens are given in IEC If necessary, 06216-1 the initial value of the property as specified in 5.
For the valid application of the standard, no transition, in particular no first-order transition should occur in the temperature range under study. The material specifications or the test standards will contain all necessary instructions for the preparation of specimens.