Gas insulated switchgear from Alstom is enabling two UAE power stations to connect to the public grid. Dubai Electricity and Water Authority (DEWA) selected the T155 Gas Insulated Switchgear on the basis of its reliability and performance in the demanding environment with high humidity and daytime temperatures commonly above 40 deg C.

The upgraded power station D in Jebel Ali and the newly built power station K, about 2km further along the coast, will both be routed through the T155, although each power station has its own transformers. There are 14 bays in the Jebel Ali T155 including two bus couplers. Three of these bays are ready for connection to the new K power station when it comes on line next year.

The T155 operates at 400kV although the T155 can be designed to operate at 550kV.

Jebel Ali's T155 is guaranteed to operate at full load in temperatures of up to 55 deg C. The 53m long and 10m wide equipment is housed in a purpose-built building, ventilated by blowers on the roof and does not need air-conditioning.

The T155 has been fitted with a number of improved safety measures. These include the use of small cameras to allow remote inspection of the disconnectors.

An on-line Partial Discharge Monitoring System has been fitted to the T155 at Jebel Ali. Using ultra high frequency this system is the most effective way to prevent possible dielectric problems. The T155 has 96 sensors to cover the complete equipment. A digital gas detection device has also been fitted to the T155 to allow accurate monitoring of the SF6 gas pressure remotely in the control room.

Maximum interconnectivity has been provided with two sets of busbars in each of the two bus sections. Each busbar takes a maximum current of 4,000 amps per phase. Foundations for another two bays have already been fitted in the floor of the building to allow for expansion.

Operation of the T155 is from a remote control room located in an adjacent building. Alstom T&D in the Gulf has a dedicated team based in Sharjah and Abu Dhabi that is prepared to meet the current level of expansion throughout the Gulf.

In 10 years in the Middle East, Alstom has expanded to capture 25 per cent of new orders for GIS sub-stations in Kuwait and the UAE and increased its market share throughout the Gulf.