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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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.
These are ISO and ISO respectively, which use less rigorous statistical procedures and more restricted experimental techniques. Values of the abscissa are proportional to the reciprocal of the thermodynamic absolute temperature. 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. Screening measurements ensure that specimens are of uniform quality and typical of the material to be tested.
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.
The large statistical scatter of test data which was found, together with the frequent occurrence of substantial deviations from the ideal behavior, demonstrated the need for tests to assess the validity of the basic physico-chemical model.
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Find out more about British Standards by visiting our website at bsigroup. Ascending order in this standard implies that the data is ordered in this way, the first orderstatistic being the smallest.
For destructive tests, see 5. 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 602162- duration of 20 A simplified procedure is available in IEC The temperature extrapolation again shall not exceed 25 K.
Organizations of all sizes and across all sectors choose standards to help them achieve their goals. If such a method cannot be found, an international, national, or institution standard, or a specially devised method should be used, and in that order of preference. 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. If these expedients are not successful, it will be necessary to test at a temperature low enough for extrapolation not to be required.
The common usage is employed throughout this standard. In the case of destructive tests 6. An approximately linear region of the ageing graph is selected Figure 3 and a line parallel to the mean ageing graph drawn through each time, jec point.
If not, the assumption is a priori rejected, but, since in special cases it is possible to detect a statistically significant non-linearity which is of little practical importance, the calculations may, under specified conditions, be continued in a modified way for details, see IEC If the decision to eic the original test programme is taken after its completion, the duration of the complete procedure may become prohibitive.
Failures at the end of the first ageing cycle cannot be accepted.
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Methods based on mean values of normally distributed test results 3 3. In obtaining the RTI, the systematic errors observed in the determination of TI are to a large extent compensated. 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.
If necessary, determine the initial value of the property as specified in 5. A 6016-2 which has frequently been found very useful involves the delayed introduction of test groups following the sequence in the Table B.
A sequential procedure may also be justified where the envisaged accuracy of the evaluation requires additional specimens to be aged, for example, in the case where the thermal endurance relationship turns out to be non-linear.
We continually improve the quality of our products and services to benefit your business. 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.
Groups are tested as indicated in the table. About us We bring together business, industry, government, consumers, innovators and others to 602162 their combined experience and expertise into standards -based solutions.
For materials in which a significant variation of properties with temperature or humidity is expected, unless otherwise specified, condition the specimens overnight in standard atmosphere B of IEC It is not necessary for all groups to be equal in size or for equal numbers to have failed.
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. However, in many cases, the deviations arise from the ageing behavior of the material; this happens with many thermoplastic materials or other materials where the ageing temperature range includes, or is close to, a transition temperature of some kind, or where there is more than one ageing mechanism at work.
If either of these conditions is not met, the value of TI cannot be reported.
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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. Determination of thermal endurance properties of electrical insulating materials Choice of test criteria Electrical insulating materials – Thermal endurance properties Part 3: 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.
However, the planned number of groups of specimens at each temperature see 5. A list of organizations represented on this committee can be obtained on request to its secretary. A time to end-point within the first ageing period shall be treated as invalid.
The knowledge embodied in our standards has been carefully assembled in a dependable format and refined through our open consultation process. A choice of properties is given in IEC In the same way, calculate the temperature? 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: 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.
Instructions for calculating thermal endurance characteristics using simplified procedures 1 1 ———————— To be published.
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
Plot these time-temperature pairs on the thermal endurance graph and draw a smooth curve passing through these points. Instructions for calculating thermal endurance characteristics using simplified procedures. The following test report forms are related: