IEC 60172 pdf – Test procedure for the determination of the temperature index of enamelled and tape wrapped winding wires
This International Standard specifies，in accordance with the provisions of IEC 60216-1, amethod for evaluating the temperature index of enamelled wire,varnished or unvarnished with
an impregnating agent, and of tape wrapped round and rectangular wire, in air at atmospheric
pressure by periodically monitoring changes in response to AC proof voltage tests. Thisprocedure does not apply to fibre-insulated wire or wire covered with tapes containinginorganic fibres.
NOTE The data obtained according to this test procedure provide the designer and developmentengineer withinformation for the selection of winding wire for further evaluation of insulationisystems and equipment tests.
The following documents are referred to in the text in such a way that some or all of theircontent constitutes requirements of this document. For dated references,only the editioncited applies.For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60216-1，Electrical insulating materials – Thermal endurance properties -Part 1: Ageingprocedures and evaluation of test results
IEC 60216-3，Electrical insulating materials – Thermalendurance properties – Part 3:Instructions for calculating thermal endurance characteristics
3Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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number which permits comparison of the temperature/time characteristics of an electricalinsulating material, or a simple combination of materials, based on the temperature in degrees
Celsius which is obtained by extrapolating the Arrhenius plot of life versus temperature to alifetime of 20 000 h
Note 1 to entry: In case of insulation systems, the temperature indx may be derived from known serviceexperience or from a known comparative functional evaluation of an evaluated and established reference insulationsystem as basis.
[SOURCE: IEC 60050-212:2010，212-12-11] modified by merging Note 1 into the definition,and to specify a lifetime of 20 000 h.]
specimen failure time
number of hours at the exposure temperature that have elapsed at the time a specimenfails the prooftest
time to failure
number of hours to failure calculated from the specimen mean value or logarithmic meanvalue failure times for a set of specimens at one exposure temperature，in accordance with8.2
4Summary of procedure
A set of specimens in accordance with Clause 5 is subjected to a testing cycle. This cycleconsists of a heat-exposure period at a temperature given in Clause 6, followed by a proofvoltage test at room temperaturein accordance with Clause 7.
This cycle is repeated until a sufficient number ofspecimens has failed. The time to failure iscalculatedin accordance with Clause 8. The test is carried out at three or moretemperatures. A regression line is calculated in accordance with 8.4 and the time to failurevalues plotted on thermalendurancegraph paper as a function of the exposuretemperature.
The temperaturein degrees Celsius， correspondingto the point of intersection of theregression line with the ordinate of 20 000 h endurance represents thetemperature index ofthe winding wire under test.
5 Test specimens
5.1.1 Enamelled non-tape wrapped round wire
This procedure applies to enamelled round wires that are not tape wrapped. The thermalindex’ can be determined by evaluating enamelled non-tape wrapped round wire with anominal conductor diameter of 0,224 mm up to and including 2,65 mm.
NOTE For round enamelled winding wires, experience has shown _ that nominal conductor diameters of 0.800 mmup to and including 1.60 mm are generally found convenient to handle and test.
Wires with a nominal conductor diameter between 0.280 mm and 0,500 mm are permitted foruse when the specification range of diameters is limited to 0,500 mm and finer.
The grade of insulation used for determining the thermal index shall be grade 2 or grade 2Bfor self-bonding winding wires.
Specimens shall be prepared as follows:
a) A wire specimen approximately 400 mm in length shall be twisted together over a distance