Inventors:
Thomas D. Walsh - Braintree MA
Nicholas Reinhardt - Lexington MA
James M. Feldman - Newton Highlands MA
George R. Vrablik - Wayland MA
Joshua Horwitz - Magnolia MA
Kathleen M. Morris - Wakefield MA
John O. Rudy - Newton MA
Assignee:
Boston Edison Company - Boston MA
International Classification:
G01R 3100
Abstract:
Method and apparatus for identifying and determining the energization status of a cable having a conductive neutral member and an internal resistive screen layer involving probes radially movable relative to the cable to contact the neutral member and the internal resistive screen. Narrow-band AC signals and resistance measurements are utilized for self-testing and for cable testing. A microprocessor controls probe-heating in the advancing of probes through plastic sheath to reach the neutral wire and resistive screen layer. Resistance measurements made under control of the microprocessor are monitored with probe advance. Oscillators provide two signals of different frequencies, one of which is that of the power being transmitted through the cable, to provide distinctive signals indicative of cable energization status.