T&D World Magazine

Northeast Utilities Strengthens its High Voltage Transmission Lines Using an Implosion Splice Method

The Connecticut Light & Power Co. (CL&P), part of the Northeast Utilities System, is replacing about 900 connectors on about 100 miles of 345-kV line using an implosion splice method, a technology new to Southern New England. The splices and dead-end connectors were originally installed over 40 years ago on the 2156 kcmil conductor using a hydraulic press and insulating paste to keep moisture out of the crimped area. Over time the insulating material has migrated out of the compressed joint, opening the way for moisture and corrosion to occur. Not every connector on these lines is being replaced. An infrared survey conducted by helicopter identified the connectors in need of replacement.

The splice technology being used is a development of IMPLO Technologies, Inc., Markham, Ontario, Canada. A primer cord, wrapped around the outside diameter of an aluminum connector is detonated. About 60 percent of the energy released in the implosion is directed inward applying about 400 tons per square inch of pressure on the connector, fusing the connector to the transmission line. The work creates a sound that is similar to the final aerial burst of a commercial fireworks display.

Specially trained crews from PAR Electric, Kansas City, MO (www.parelectric.com) install the connectors while the lines are energized – a first in the United States. The live-line work is done from specially insulated bucket trucks while the crew members wear a hooded suit with a grid imbedded into the material so the electricity flows around them. The upgrades began in the fall of 2006 and the work is scheduled to be completed late in April, 2007, weather permitting.

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