Apparatus for establishing and maintaining electric continuity in drill pipe

摘要

Apparatus for use in a rotary drill string to maintain electric continuity therethrough includes an externally insulated electric conductor tube having an electric cable mounted therein. The cable is telescopically movable with respect to the tube, and its lower end is in sliding contact with the interior of the tube. As drilling progresses, the cable may be extended relative to the tube, the sliding contact of the lower end of the cable maintaining electric continuity in the system.