Electrochemical treeing is known to be a major cause of failuresin cross-linked polyethylene cables. One method of preventing treeing isa moisture impervious layer on the cable. The on-core moistureimpervious cable design is commercially available and has a largeinstalled base. Much research has been done in the laboratory on themoisture impervious cable but little testing of field-aged cables hasbeen done. The first phase of an ongoing test program of field-agedmoisture impervious cables is described. Samples were removed from fieldservice at a US electric utility in order to begin evaluation offield-aged cables. Also tested were new (1990) and unaged (1984) samplesof the same construction as a control. AC high voltage breakdown,lightning impulse breakdown and switching impulse breakdown wereperformed. Also, material analyses were performed for comparison. Thesetests were begun in order to develop a database to demonstrate thelong-term performance of on-core moisture impervious cables. The resultsfrom these preliminary tests indicate that on-core moisture imperviouscables perform well in the field
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