Nonintrusive sensing techniques for the discrimination of energized electric cables

The implementation of a piezoelectric acoustic sensor for nonintrusive detection of the energization status of 3-/spl phi/ electric power cables is presented. Simultaneous excitation of a piezoelectric crystal by acoustic vibrations and electric field may occur. The Fourier spectral analysis of the sensor's output signal is used to determine the current loading status of the cable. Test results are included for both shielded and nonshielded 3-/spl phi/ cables. Also, the possible use of an optical fiber interferometer for acoustic wave detection is discussed.