| 摘要 |
A control circuit 61 controls the power feed through an electrical wire 5 by ON/OFF switching of a FET 60 situated midway along the electrical wire 5. On the basis of a previous temperature difference between a previously calculated ambient temperature and electrical wire temperature of the electrical wire 5, and the value of the current flowing through the electrical wire 5, a control unit 70 calculates a time series of temperature differences between the ambient temperature and electrical wire temperature of the electrical wire 5. The control unit 70 is configured so as to pause this time-series calculation of temperature differences, and after pausing calculation of temperature differences, to measure the time elapsed until the calculation is resumed. In the event that calculation of temperature differences has resumed, the control unit 70, on the basis of the measured elapsed time, sets the initial temperature difference employed as the previous temperature difference in the initial calculation of temperature difference following resumption. |
