Posted: February 29th 2016

Extreme makeover – substation edition

Sometimes new is better, even when it means completely replacing an existing facility that serves many customers.

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Sometimes new is better, even when it means completely replacing an existing facility that serves many customers. That’s exactly what is happening with the Tewksbury 22A Gas Insulated Substation located in the Merrimack Valley area of Massachusetts.

The existing substation was built in the 1970s and serves customers in cities and towns in eastern Massachusetts. Two 345 kilovolt lines come into the station, bringing power from generating stations; four other transmission lines deliver power from the substation to other facilities in the area.

The existing substation is part of the first generation of gas-insulated substations, which were built completely outdoors. This left them exposed to the New England weather, which as we all know sometimes features extreme cold and heat, along with ice and biting winds.

Temperature does not typically affect regular open-air substations; however, it can be an issue for gas insulated stations and can lead to significant wear and tear on these facilities, especially the gas-insulated equipment.

Since the first generation of gas insulated substations were built, the technology has advanced so the gas-insulated components can now be completely enclosed within a temperature-controlled building, eliminating the exposure to bad weather and reducing potential equipment damage and degradation. So the Tewksbury 22A substation is getting a major makeover into a new, state-of-the art facility.

The new substation is being designed with our customer needs in mind by sizing the building to sufficiently house equipment to accommodate additional transmission lines that may be needed at some point in the future. A fifth transmission line currently is in the siting and permitting stages and is expected to be built in the next couple of years.

“Our customers trust us to provide reliable service, and this project will enable us to continue to do just that,” said Mike Szczepanek, manager, Substation and Civil Construction in the Project Management and Complex Construction group. “The new substation will require less maintenance, operate more efficiently and will help us continue to connect customers to the power that they need.”

Tewksbury 22A Gas Insulated Substation Replacement Project Timeline

2015 –

  • August – Tree clearing and installation of environmental protections
  • Fall – Foundations installed for the new GIS building and two control rooms plus as several foundations for the gas insulated bus and transmission towers
  • October – December – Buildings were constructed

2016 –

  • January – The GIS building floor was installed, which required about 400 yards of concrete continuously poured for just under nine hours.
  • February – September – Installation of substation equipment including circuit breakers, gas insulated bus, control panels, protective relay and alarm systems – and transmission towers.
  • October – December – Substation will be energized and tested

2017 –

  • January – Removal of existing substation and completion of project
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“Our customers trust us to provide reliable service, and this project will enable us to continue to do just that”

Mike Szczepanek, manager, Substation and Civil Construction in the Project Management and Complex Construction group