Analysis of Behaviour of Phase S Capacitive Tap Insulator of Interconnection 1,220 kV, in Jinamar Power Plant (Island of Gran Canaria, Canary Islands, Spain)

In the island of Gran Canaria, Canary Islands, there are two Power Plants called Jinamar Power Plant and Barranco de Tirajana Power Plant, both property of Unelco Generacion, a subsidiary of Endesa Generacion. The first one is placed in the northeast of the island, near its capital, Las Palmas de Gran Canaria, and the other is in the southeast, near the most significant touristic area of the island. Both plants are interconnected by means of four transmission lines, two with a voltage of 220 kV and the other two with 66 kV. Since its commissioning in 1995, several phase to ground shortcircuits have occurred in one of the capacitive tap insulators in the 220 kV lines, in Jinamar side, without a clear cause for them, causing problems of different kind in the electrical system of Gran Canaria. From construction of tap insulators to environmental conditions, every possible factor was carefully studied and laboratory tests were made. In this paper it is described the analysis that was carried out and how a deep study of every possible cause drove to a definitive solution of the problem.