Abstract: A method is provided for utilizing a nonintrusive, noncontacting electric field sensing device to detect faults in high voltage transmission line insulators. The electric field surrounding an unfaulted insulator is mapped using a spherical dipole to obtain a characteristic reference curve. The field of a suspect insulator is then mapped to obtain a test curve which is compared with the reference curve to determine the existence of and location of a fault.

Abstract: A position sensor for a moving member of a mechanical device is disclosed. The sensor includes an optical sensing means such as solid-state image sensor and illuminating means such as a plurality of light-emitting diodes, stationarily mounted to face scribing marks provided on the moving member. The microprocessor controlled image sensor generates a digital signal representative of the scribing marks on the moving member. A cable is provided between the position sensor and a remote digital computer which applies control and command signals to the sensor and receives the digital signal representation of the moving member scribing marks. The image is presented on a CRT screen allowing a human being a remote visual image of the position of the moving member. The remote digital computer also processes the received digital signal from each of the moving members and generates an alarm if the movement is greater than a predetermined amount.