Replacement of Pipe Type Cables with Cross-Linked Polyethylene (XLPE) Cables by Utilizing the Existing Steel Pipe

Abstract

High-pressure fluid-filled (HPFF) pipe type cables make up the bulk of the underground transmission lines in North America. These cable systems started to enter commercial operation in the early 1930s and many are now beyond their design life. Although HPFF cables have provided excellent reliability, some now suffer from corrosion, leaks, and failures. HPFF cables also present system design complexity and require highly skilled personnel for operation, maintenance, and repair. Utilities in North America now face the technical and economic challenges of replacing this infrastructure to maintain reliability of supply. This paper addresses replacement using XLPE cables by re-utilizing the steel pipe and manhole system in order to reduce cost and minimize impact to traffic and stakeholders by eliminating the need to construct new lines. The paper presents constraints on pipe inside diameters, limitations on XLPE cable diameters, insulation thicknesses, cable operating stresses, and ampacity and bonding options.