Brugg Cables, from Switzerland, announced the successful commissioning of their first 345-kV XLPE underground cable installation in the United States. Earlier this year the new system was provided to NSTAR, the electric and gas utility serving customers in the Boston, MA area and Eastern Massachusetts. This connection is part of the larger NSTAR 345-kV Transmission Reliability Project designed to enhance the region’s electrical capabilities. The 345-kV XLPE system consists of two circuits between newly installed 345-kV transformers and reactors and 12 terminations installed at the K Street Substation in South Boston. An XLPE cable solution for these tie lines was chosen because of space limitations and the urban location of the substation.

The 345-kV XLPE cable was produced at Brugg’s facilities located in Brugg, Switzerland approximately 20 miles northwest of Zurich. The cable is designed for a continuous transmission load of 600 MVA per circuit and was supplied with a copper corrugated sheath for added strength and flexibility. The cable was laid in PE conduits and protected by a concrete cap above. The installation was done by Mass. Electric Construction Co. under the supervision of Brugg Cables.

The importance of this installation to the overall 345-kV Transmission Reliability Project required special attention to long- term reliability aspects of the cable system. For instance, in order to provide additional system protection, each of the 12 terminations was equipped with a newly developed partial discharge (PD) sensor based on UHF technology. These sensors allow the system operator to monitor and assess the condition of the terminations at any time and thus allow him to make decisions well in advance of any problems that may occur during operation.

“We are proud that we were selected by NSTAR as the supplier for this challengingproject,”said Frank Tomczyk, Brugg Cables LLC, National Sales Manager for the U.S. market located in Rome (GA). “Providing a proven, reliable and environmentally friendly cable solution together with highest quality accessories for this important project will further encourage U.S. utilities to specify XLPE underground cable for their future EHV requirements.”