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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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 material specifications or the test standards will contain all necessary instructions for the preparation of specimens. 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.
To provide uniform conditions, the conditioning of specimens after removal from the oven and before measurement may need to be specified. 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.
Ageing procedures and evaluation of test results 1 Scope This part of IEC specifies the general ageing conditions and procedures to be used for deriving thermal endurance characteristics and gives guidance in using the detailed instructions and guidelines in the other parts of the standard.
In such cases it is often convenient to start by loading the ageing oven with one-half of the prepared specimens and jec measurements after the second or third exposure cycle of the recommended series. Revisions Our British Standards and other publications are updated by ieec or revision. A flow chart and decision table setting out the procedures and conditions are given in Annexes A and B of IEC These further tests may be at lower or intermediate temperatures but should not generally be at higher temperatures than originally selected.
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Although ic 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.
Generally, the following instructions 5. Values of the abscissa are proportional to the reciprocal of the thermodynamic absolute temperature. The y -values derived are used in the calculations of 6. If this rule results in changes of mechanism for example, when a transformation point like melting or softening is exceededthen ice maximum exposure temperature will need to be limited. In this case, cycle times of 56 days, or even more, may be required.
In some cases for example, very thick specimenstimes greater than two days may be necessary to establish a stable value.
This publication does not 60216-22 to include all the necessary provisions of a contract.
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 This value might be selected with respect to usual service requirements. In either case, the specimen preparation technique should be carefully examined. 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.
Do you need a multi-user copy? These are ISO and ISO respectively, which use less rigorous statistical procedures and more restricted experimental techniques. About us We bring together business, industry, government, consumers, 60216- and others to shape their combined experience and expertise into standards -based solutions.
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
In all cases, ageing shall be continued until more than one-half of the test specimens in each group have failed to pass the proof test.
If you need international 6216-2 foreign standards from other Standards Development Organizations, hard copies can be ordered from our Customer Services team. If the results do not show this, the period may be changed so that the median result may be expected in at uec seven cycles preferably about 10 provided this change in cycle time is made before the fourth cycle. Methods based on mean values of normally distributed test results 3 3.
A list of organizations represented on this committee can be obtained on request to its secretary. The characteristic has now been made the subject of a new, independent standard in preparation. Where there is no risk of ambiguity, either ied groups or test groups may be referred to simply as groups.
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Before determining the property value, these specimens shall be conditioned by exposure to the lowest level of ageing temperature of the test see 5. This sixth edition cancels and replaces the fifth edition, published in A choice of properties is given in IEC The following dates are fixed: 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 For the valid application of the standard, no transition, in particular no first-order transition should occur in the temperature range under study.
This approach will provide comparisons among materials but bears a poorer relationship than item b to the property values required in normal service. In such cases, or if the value of HIC is known or expected to be less than 10 K, the difference between the levels of ageing temperature may need to be reduced, but to not less than 10 K so that oven temperature tolerance effects will be acceptable.