When determining a transmission line route through a given area, the choice of available power transmission methods may become limited....
Every station layout design has certain physical boundaries to which the transmission components must adhere. If the space available precludes the use of air-insulated bus, and the lack of available land prevents continuous a transmission line at ground level or below grade, one solution is to elevate the bus system. The Teesside Power Plant is an example of this type of installation

Teesside Power Plant
The Teesside Project is a 1725 MW combined-cycle gas-fired power plant located in the United Kingdom. The arrangement of the generators and transformers, and the location of the gas insulated switchgear created a need for an extensive array of 275 kV, 1200 amp transmission links from transformers to enclosed GIS substation.

The amount of space available for power transmission was very limited. An installation below grade was not possible due to the existing system of underground lines, steam pipes, etc. In addition, the water table in this region was located approximately three feet below grade prohibited underground transmission.  A ground-level arrangement was not possible due to roadway requirements.

The solution  was an elevated compact GIB system. CGIT was selected because of our reliability and experience at these system ratings. 

What made this project unique for CGIT was the height requirement. Due to the proposed structures and access requirements, the CGIT system  ran at elevations as high as 29 feet above grade. Support structures for this project were designed to hold as many as five circuits (fifteen phases) of bus, with at least six phases running at the maximum height.

One important consideration in the bus layout and piping analysis of the system was thermal expansion of the enclosure. Most systems must accommodate the enclosure growth experienced due to temperature rise. This can be accomplished using expansion bellows, but at an elevation of 29 feet, the supporting requirements to withstand the pressure thrust of an expansion bellows would be prohibitively expensive, and would create excessive foundation loads. Another option is to fix the bus near the mid-point of each long run, to direct the growth toward an elbow. In this case, the flexibility of the mitered elbows allowed sufficient growth, eliminating the need for expansion bellows. The Teesside Project, consisting of over 18,000 phase feet of SF₆ gas insulated bus , was installed and commissioned in 1992.

The photo below shows the installation application and overall view of the CGIT system at Teesside.

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