Statistical analysis of the test procedure for the evaluation of the thermal endurance of winding wires

The present paper covers the test procedure for the evaluation of the thermal endurance of enamelled wires. This procedure has been specified in the IEC publication 1721 and the corresponding national standards. The statistical errors given by the test material and the influence of the temperature deviations are being investigated. For this purpose 208 series of measurements with a total of 4000 specimens were observed and computed by means of a Hewlett-Packard Calculator 9100. It is demonstrated that the results are not altered, if median instead of logarithmic mean values are used. This also applies particularly, if the limits of ±2 °K for the maximum temperature tolerance in the ovens as defined in the relevant standards are considered.