| 摘要 |
<p>Method for determining cable faults in an electric heating cable comprising at least two well conductive lines having an electrical resistor material in between them and electrically connected to the conductive lines in order to dissipate power over mainly the whole length of the cable when connected to an electric power source. Such cable fault may be caused by electrical disconnection between the resistor material and the conductive lines, resulting in interruption of the power dissipation there. The method comprises the steps of
a. sending an electrical signal having a predetermined electric power P A , from a location A to a location B of the cable and determining the power P A of the signal arrived at location B,
b. sending an electrical signal having the predetermined electric power P A , from location A at a moment T 1 , as well as sending an opposite electrical signal having a predetermined electric power P B from location B at a moment T B which is chosen such that the first signal and the opposite signal meet each other at a predetermined location C between the locations A and B, and determining the power P A " of the signal arrived at location B,
c. comparing the power P A " of the signal arrived at location B determined in step b. with the power P A ' of the signal arrived at location B determined in step a. and concluding either that if P A " is lower than P A ', location C is not faulty, or if P A " is not lower than P A ', location C is faulty.</p> |
