Eversource Greater Hartford Central Connecticut Reliability Project

Various locations, ct

The global scope of the Greater Hartford – Central Connecticut Reliability Project is to construct a new underground 115kV transmission line in the Greater Hartford and Central Connecticut area. These improvements will strengthen the electrical system and ensure customers have reliable power to meet the higher energy needs and also keep up with national and regional reliability projects. The 3.8-mile underground line would be constructed between the Newington Substation and Southwest Hartford Substation. Several substations would have to be upgraded as a result of this reliability project. Some projects that AI Engineers, Inc. (AI) is reviewing on Eversource Energy’s behalf of the drawings and calculations prepared by vendors are as follows:

  • Berlin Substation Reconfiguration
  • Newington Substation Line Terminal Relocation
  • Southwest Hartford Substation Reactor Installation
  • Branford Substation Modifications
  • Green Hill Substation Modifications
  • Hopewell Substation Capacitor Bank Installation
  • Southington Substation Modifications

The latter project plays a large part on the Greater Hartford - Central Connecticut (GHCC) project underway to improve reliability and eliminate potential thermal criteria violations within the system in Northwest Connecticut, Manchester-Barbour Hill, Greater Hartford, and Middletown.

The proposed Greater Hartford area solution includes the several upgrades within the Southington substation 115kV and 345kV yards including the construction of a new 115kV relay and control house. These upgrades at the Southington substation and the other components of the Greater Hartford proposed solution will mitigate the identified N-1 and N-1-1 contingencies and improve reliability in the Greater Hartford area.

This project consists of four components: the addition of a new 3% bus tie reactor between Ring 1 and Ring 2 in the 115kV substation yard, installation of a new 115kV relay and control enclosure, replacement of the existing 1910 and 1950 3% line reactors with new 5% reactors, and installation of one new 345kV circuit breaker adjacent to the existing 5T circuit breaker in the 345kV substation yard. 


  • Duration: 2013 - Present
  • Project Scope:
    • Underground 115kV transmission line
    • Shop drawing reviews
    • Coordination with owner