engleski

Some peculiarities in insulation coordination and mitigation measures against extreme sea salt pollution on Croatian 110 kV "Islands connection"

Among Croatian transmission lines (rated voltages of 110 kV, 220 kV and 400 kV) one combined 110 kV line (OHL+submarine cables) is particulary interesting due to its characteristics and environmental influences to which it is exposed. It is s.c. '110 kV Islands Connection', a combination of overhead lines and submarine cables between great towns Rijeka and Zadar on Adriatic coast passing over great islands Krk, Rab and Pag (with one branch over islands Cres and Lošinj) in total lenght of about 170 km (including about 30 km of 4 sections of submarine cable). There are four 110 kV 'passing or tapped type' substations on islands (RP Omišalj, TS Rab, TS Pag and TS Nin), two 'meshed type' (TS Krk and TS Novalja) - all in AIS version - and eight 110 kV s.c. 'cable houses' or 'cubicles' (transitions: submarine cable - OHL) with 110 kV bushings. High voltage equipment - particulary outdoor insulators - in open space and even in 'cable houses' are exposed to extreme sea salt pollution from the nearby Adriatic Sea. From the very beginnigs of operation (now more than 10 years ago) the special attention have been paid to that combined long 110 kV line due to its operational and environmental stresses and frequent outages or faults. It is worth therefore to present some expiriences and to be comparable with similar cases from the world. In this article will be given analysis for the northen part of 'Islands Connection' (from town Rijeka and its substation TS Meline to substation TS Novalja on island Pag), because that section is the most exposed.

Insulation coordination; Transmission network; Sea salt pollution; Submarine cable; Overhead line; Outdoor insulation; Bushings; Metal-oxide arresters; Faults; System protection; Spark gap

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