Case Study: Amesbury #5 Substation Power Transformer Fmergency Relocation

The objective of this paper is to review the design and execution of an emergency transformer relocation at National Grid's Amesbury #5 substation. The Amesbury #5 substation is a 23kV to 4kV station located in Amesbury, Massachusetts. This station is the sole source of power feeding the downtown Amesbury area, including but not limited to, the Town Hall, Police Station and Fire Station. This station is located on the site of a pre-existing mill building and hydroelectric generation plant that was demolished in the early 1900s. The site is tiered and consists of two retaining walls; the lower retaining wall, adjacent to the Powwow River, has reached a deteriorated state. Transformer 2 (T2) containing 6,261 L (1,654 gal) of oil and weighing 24,472 kg (53,950 lbs.) was situated directly on top of the lower retaining wall. In the event of a wall failure, T2 was at high risk of falling into the river. Recently, a significant amount of soil loss was observed within the station yard which triggered a combination of invasive and non-invasive investigations to evaluate the stability of the site. The result led to the emergency relocation of T2 to a more stable location. The station reconfiguration and transformer relocation was designed and executed in a matter of months by the National Grid team.