Laboratory Evaluation of 345-kY Cable 2 High-Pressure Oil-Filled Pipe-Type After Field Testing at Cornell University

Upon completion of the 345-kV field test at the Cornell Test Station, representative sections of the high-pressure pipe-type cable supplied for the test by the authors´ company were subjected to laboratory evaluation. No indications of instability or significant deterioration resulting from the field test were found. The returned cable withstood the standard high-voltage-time test for new cable and had slightly lower power factor at all temperatures than it had before being tested, as well as essentially unchanged radial power-factor distribution. Mechanical properties and dielectric strength of the paper were not significantly affected. No electrical disturbance of any kind was found in the cable proper or in the joints; however, there was slight carbonization in the vicinity of electrode interruptions provided for power-factor measurement and also at the base of the paper buildup in one of the terminals. Both the-saturating oil and the pipe oil were in essentially the original condition. Apparently, however, some of the pipe oil had migrated into the cable from the potheads because of expansion and contraction incident to load cycling.