Siemens Energy, Inc. has been awarded a contract by Northeast Utilities for 115-kV and 345-kV gas-insulated transmission lines (GITL) for the Agawam (Massachusetts) and North Bloomfield (Connecticut) substation additions as part of the Greater Springfield Reliability Project, one of four major transmission projects comprising the New England East-West Solution (NEEWS).

The project is designed to address transmission system overload and meet current federal and regional reliability standards. For the GITL portion of the project, Siemens will provide all engineering, design, assembly, construction and commissioning activities, including the technical studies, controls design, apparatus testing and quality management. Construction on the Greater Springfield Reliability Project started in substations in Massachusetts in late 2010 and will start in Connecticut in late 2011. The estimated in-service date is 2013.

"Siemens is pleased to be a part of this significant leap in transmission reliability that Northeast Utilities is bringing to its customers in Massachusetts and Connecticut," said Frank Petraglia, Vice President and General Manager of the High-voltage Substations business of Siemens Energy, Inc. "Our GITL technology is an ideal alternative to overhead lines. The simplicity of GITL design and the fact that it is designed to require very little maintenance ensures a long service life for Northeast Utilities."

Siemens will build five circuits at two air-insulated substations (AIS) located 17 mi apart in Massachusetts and Connecticut for Northeast Utilities for a total length of 1 mi. Northeast Utilities will implement GITL technology at two different substations. The Agawam substation will contain two circuits at 345 kV and two circuits at 115 kV, while the North Bloomfield substation will use one circuit at 345 kV. The GITL is fitted with elbows and angle adjustment components to simplify the foundation design and use standard precast trenches. The GITL design minimizes the overall civil work costs for Northeast Utilities.

"Siemens' innovative GITL technology utilized in the NEEWS project will help Northeast Utilities increase the reliability of electric power in southern New England and the region overall and allow access to cleaner, competitively priced electric power," said Laurie Aylsworth, Vice President, Transmission Projects, Engineering and Maintenance, Northeast Utilities.

The GITL will run underground and then connect to above-ground bushings on both AIS. The GITL technology carries high current ampacity on one single conductor, whereas the same current would need two or three cables in an AIS application. GITL has significantly lower losses, a lower magnetic field and no risk of burning compared to cables or overhead lines.