| 摘要 |
<p>A sample of electric wire is sampled from an operating roadway, a correlation of evaluation standard among an electric wire temperature, a heating time and a residual strength is obtained by giving a heat history consisting of plural temperatures to this sample and, on the basis of this correlation, a working temperature of an operating line is determined. When this correlation is obtained, it is preferable that from its result, each of constants A, B and C is obtained such that a relation between the heat history exp {A•T-B+C•1n(h)} and the evaluation standard of the residual strength becomes linear. Incidentally, T denotes the electric wire temperature (°C), and h the heating time (hrs). This method can determine a thermal proof strength of the electric wire more accurately depending on the state of the roadway.</p> |
