Water Trees in Cross-Linked Polyethylene Power Cables

Water trees are considered to be one of the main reasons for faults of polyethylene-insulated cables. They are found in service and laboratory. It is confirmed that they are caused by the co-existence of both electric field and water. Their formation would reduce breakdown strengths of cables. Dielectrophoresis is concluded as a possible mechanism for the aggregation of water around the high electric field regions. It may be followed by the formation of water trees. The growth mechanism of water trees is discussed and temporal countermeasures against them are referred to.