Long term test of buried gas-insulated transmission lines (GIL)

In order to prove the electrical, thermal and mechanical layout of directly buried gas-insulated transmission lines (GIL), a long term test was carried out at the test field of IPH in Berlin, Germany. A single phase was buried and subjected to the cycles of higher current of 4000 A and higher operation voltage of 480 kV to simulate 50 years of life time. Electrical, thermal and mechanical measurements have been carried out and compared with the numerical simulation. In this article some comparisons of measured and calculated values are presented.