IEC 60216-5-2003 pdf – Electrical insulating materials – Thermal endurance properties – Part 5: Determination of relative thermal endurance index (RTE) of an insulating material.
1 Scope This part of IEC 60216 specifies the experimental and calculation procedures to be used for deriving the relative thermal endurance index of a material from experimental data obtained in accordance with the instructions of IEC 60216-1 and IEC 60216-2. The calculation procedures are supplementary to those of IEC 60216-3. Guidance is also given for assessment of thermal ageing after a single fixed time and temperature, without extrapolation. The experimental data may in principle be obtained using destructive, non-destructive or proof tests, although destructive tests have been much more extensively employed. Data obtained from non-destructive or proof tests may be “censored”, in that measurement of times taken to reach the endpoint may have been terminated at some point after the median time but before all specimens have reached end-point (see 3.1 of IEC 60216-3). Guidance is given for preliminary assignment of a material to an insulation class, based upon the thermal ageing performance. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60216-1:2001, Electrical insulating materials – Properties of thermal endurance – Part 1: Ageing procedures and evaluation of test results IEC 60216-2:1990, Guide for the determination of thermal endurance properties of electrical insulating materials – Part 2: Choice of test criteria IEC 60216-3:2002, Electrical insulating materials – Thermal endurance properties – Part 3: Instructions for calculating thermal endurance characteristics 3 Terms, definitions, symbols, units and abbreviated terms For the purposes of this part of IEC 60216, the following terms, definitions, symbols, units and abbreviated terms apply.
3.1 Terms, abbreviations and definitions 3.1.1 assessed thermal endurance index ATE numerical value of the temperature in degrees Celsius, up to which the control material possesses known, satisfactory service performance in the specified application NOTE 1 The value of the ATE may vary between applications for the same material. NOTE 2 Sometimes referred to as “absolute” thermal endurance index. 3.1.2 candidate material material for which an estimate of the thermal endurance is required to be determined NOTE The determination is made by simultaneous thermal ageing of the material and a control material. 3.1.3 control material material with known thermal endurance, preferably derived from service experience, used as a reference for comparative tests with the candidate material 3.1.4 central second moment of a data group sum of the squares of the differences between the data values and the value of the group mean divided by the number of data in the group 3.1.5 correlation time estimated time to endpoint of the control material at a temperature equal to its assessed thermal endurance (ATE) in degrees Celsius 3.1.6 degrees of freedom number of data values minus the number of parameter values 3.1.7 standard error standard error of an estimate of the true value of a data group property is the value of the standard deviation of the hypothetical sampling population of which the group property may be considered to be a member NOTE 1 For the group mean it is equal to the group standard deviation divided by the square root of the number of data in the group, and indicates the uncertainty in the true value of the mean. NOTE 2 This standard is concerned only with means and the difference between two means (see Clause A.2). 3.1.8 standard deviation square root of the variance of a data group or sub-group