Project in submarines hyper high-voltage cables   

The project:

Fulgor SA, a member of Stasinopoulos group of companies, started the manufacturing of submarine high voltage cables, up to 200,000 Volts, for the transmission of electrical power under seawater.

The project was implemented at Fulgor Plant in Korinthos, Greece.

Our company undertook the de-gassing process, the construction of a system that accelerates the polymerization process and the controlled extraction of methane gas.

The degassing processes:

Each pole of the submarine cables has a copper core inside a polyethylene insulation of approximately 120 mm thickness.

The polyethylene insulation is externally covered with a lead protective coating of 3 mm thickness for sealing against the sea water.

Polyethylene insulation releases methane gas during its polymerization process; at normal temperatures the polymerization process takes one or two years.

It is absolutely necessary to complete the polymerization process of polyethylene within several days, before covering with lead protection. 

If the polymerization process continues after the application of the lead protective coating, the released methane gas can pierce the lead coating and, therefore, the submarine cables can be destroyed by the seawater in the depths of the sea.

Our task was:

• to achieve uniform heating at + 70 ° C of the whole batch of cables batch weight 1,200 tons max.
• to discharge a quantity of hot air into the environment in order to keep the concentration of methane in the hot air below the explosion levels.
• to achieve the non-explosiveness of hot air with the lowest possible energy consumption.

The application study was done by our company and required high expertise and significant experience on the degassing systems design & application. The results are more than satisfying, and the product comes out in perfect condition despite the complicated requirements. Moreover, we achieved a cost reduction on electricity about 700 € per day as well as significant decrease on fuel consumption.