The Taleqani-Sajjad utility tunnel went on stream in Mashhad, the capital of Khorasan Razavi Province, on Saturday, said managing director of Khorasan Regional Electricity Company.
Mohammad Hassan Motavallizadeh added that the 3-km-long tunnel was drilled between Sajjad and Taleqani regions at an estimated cost of $6.5 million.
According to Motavallizadeh, the 60-Megavolt-ampere gas insulated substation in Sajjad has two transformers, which is connected to Taleqani's 132-kilovolt substation via the tunnel using 19.2 km of 132-kilovolt double circuit cables, Tasnim News Agency reported. Highlighting the high price of land in this city, the official noted, "Khorasan Regional Electricity Company has taken steps to construct high voltage substations in certain parts," he said.
"Conventional substations are built in 10,000 square meters of land, whereas a GIS does not need more than 1,000 square meters.
Motavallizadeh noted that such tunnels not only help supply the new subscribers with electricity but also reduce electricity wastage and increase reliability of power grids.
Speaking on the sidelines of the inauguration ceremony, Deputy Energy Minister Houshang Falahatian said, "Khorasan Razavi Province exports 800 megawatts of surplus electricity, in addition to providing its household and industrial subscribers."
According to reports, more than 50,000 new subscribers are added to Khorasan's electricity grid per annum.
A GIS is a high voltage substation in which the major structures are contained in a sealed environment with sulfur hexafluoride gas as the insulating medium. The technology originated in Japan where there was a substantial need to develop technology to make substations as compact as possible.
The clearance required for phase to phase and phase to ground for all equipment is much lower than that required in air insulated substation; the total space required for a GIS is 10% of that needed for a conventional substation.
Gas insulated substations offer other advantages in addition to the reduced space requirements. Because the substation is enclosed in a building, a GIS is less sensitive to pollution, as well as salt, sand or large amounts of snow. Although the initial cost of building a GIS is higher than building an air insulated substation, the operation and maintenance costs of a GIS are less.
