One of the biggest challenges facing utilities as they seek to improve and expand their physical infrastructure is acquiring land upon which to build. Right of way acquisition is among the most difficult, time-consuming steps in getting a new project completed. For that reason, we increasingly see utilities trying to make the best use of the space they already have when embarking on a project to upgrade the grid.
A prime example was reported on in the last issue of Utility Automation & Engineering T&D (November/December 2005 issue). A number of large utilities, Xcel Energy and Alabama Power among them, are installing new high-capacity transmission conductor as a way of pushing more power through existing rights of way, as opposed to acquiring more land to build new transmission corridors.
Those same space considerations are also coming to the fore as utilities look to make new switchgear purchases. According to a recent study by Newton-Evans Research Company of Ellicott City, Md., a majority of utilities who are choosing gas-insulated over air-insulated switchgear are making those decisions based on space considerations and constraints. The compact nature of gas-insulated switchgear, it seems, is proving to be a positive for utilities tight on space.
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Newton-Evans completed a study in the first half of 2005 to determine the current use of gas insulated switchgear (GIS) in large U.S. electric utilities. One topic encompassed in the study included influencing factors that affected the responding utilities decisions to purchase gas insulated switchgear over air insulated switchgear (AIS).
On the survey, respondents were asked “What factors influence your utility’s decision to purchase gas insulated switchgear over air insulated switchgear? The six factors listed on the survey were:
1. space consideration/constraints,
2. safety issues,
3. initial GIS cost vs. AIS cost,
4. O&M costs of GIS vs. AIS costs,
5. life cycle of GIS vs. AIS, and
6. land purchase.
Responding utilities were in general agreement that space considerations and constraints were the most important factors influencing their decisions to use GIS equipment in substation applications, as indicated by nearly nine out of 10 utilities responding to this question (see graph). This was followed by land purchase, mentioned by 43 percent. All other factors received less than a 10 percent mention rate.
Other write-in responses to the survey question included aesthetics (three mentions), seismic, and more reliability and capability in the same space.<<
