Switchgear under surveillance5 April 2002
T155 gas insulated switchgear made by Alstom is in the grid connector circuits for two units of the Jebel Ali power station, Dubai. The upgraded unit D as well as the currently-under-construction unit K, 2 km away, will both be routed through the T155, although each unit has its own transformers. The T155s were chosen for their reliability and ruggedness in the extreme coastal desert conditions where high humidity and daytime temperatures above 40°C are the norm. The Jebel Ali switchgear is designed to operate at temperatures up to 55°C, and is housed in a mechanically ventilated enclosure without air conditioning. The installation has 14 bays, three of which awaiting connection with unit K in 2003. The switchgear operates at 400 kV, although it is also suitable for 550 kV.
New safety measures for this model include the mounting of small remote cameras to allow visual inspection of the disconnectors; and the inclusion of a partial discharge monitoring system. Using UHF, this system has 96 sensors and is considered the most effective in preventing dielectric problems. In addition a digital detector has been fitted for remote monitoring of SF6 gas pressure.
Maximum interconnectivity has been provided by means of two sets of busbars in each of the two bus bays. Each busbar takes a maximum of 4000 A per phase.