Evaluation of methods for discrimination of energized underground power cables

The maintenance and repair of underground cable power networks often requires the discrimination of energized cables among a group of unenergized ones. Presently, an invasive detection method is performed which requires utility personnel to puncture the protective cable shielding, creating a potentially hazardous situation. This paper presents a noninvasive approach for energized cable detection based on the electrically induced acoustic waves inside of the cable. The influence of background electric fields on the performance of this approach is studied. In addition, the use of a fiber optic acoustic sensor would significantly increase the safety of the detection procedure, borrowing on the intrinsic electrically insulating properties of optical fibers (i.e. dielectric, immunity to electromagnetic interference, etc.). Feasibility studies and preliminary experiments were performed using a fiber Fabry-Pérot interferometric acoustic sensor. The performance of the fiber optic sensor is compared with that of a piezoelectric accelerometer. A detailed analysis of the test results is included. Recommendations are given for correct interpretation of test results based on the specifics of a power system and sensor type.