| 摘要 |
PROBLEM TO BE SOLVED: To easily and surely diagnose the insulation deteriorated state of a power cable direct-coupled to an underground apparatus, for example, even a local deterioration by deterioration of water tree. SOLUTION: In this device, the voltage applied to the power cable direct- coupled to an underground apparatus direct-coupled terminal 2 is detected as a voltage signal by the voltage induced in a voltage detection part 11, and an earthing conductor current carried to the earthing conductor 12 of the power cable 1 is detected by a CT 13. A loss current arithmetic part 33 calculates the loss current of the same phase as the detected voltage signal from the voltage signal and current signal, and a deteriorated state diagnostic part 43 diagnoses the deterioration of the power cable 1. Accordingly, since the voltage and earthing conductor current of the power cable are detected without providing any detecting means or the like on the power cable 1 or imparting an external signal or the like, and the loss current is detected on the basis of the voltage and earthing conductor current of the power cable 1, the insulation deteriorated state of the power cable direct-coupled to the underground apparatus, for example, even the local deterioration by deterioration of water tree can be easily and surely diagnosed.
|
