(A joint technical paper by Delhi Transco Limited; & Reliance Infrastructure Limited-Mumbai Transmission)
Online published on 12 January, 2015.
With economic growth & change in life style the per capita growth in electricity consumption in the urban areas has increased significantly. Bulk power transmission is now become a part of the urban infrastructure.
Due to environmental issues and due to non-availability of adequate ROW (Right of Way) in the congested urban areas, bulk power transmission through EHV overhead lines is not possible. The required corridor of 35 m for overhead double circuit transmission line at 220 kV level is not viable; whereas cables can be laid in 2 m corridor under the ground. The only practical alternative is to lay EHV cables in underground trenches. However, EHV underground cable laying/execution in predominately congested cities of developing countries pose challenges owing to other peripheral concerns.
The paper covers case studies of various projects pertaining to two metropolitan cities (Delhi & Mumbai) with respect to 220 kV underground cable systems and briefly illustrates: Challenges overcome for laying EHV cable covering technical specifications, detailed engineering processes and usage of effective skills of influencing and decision making. Transition of cable installation from “Open Trench” to institutionalization of threading of cable through concrete encased Duct Bank Installation.
Vertical gantry facilitating jointing of EHV overhead lines with EHV cables by installing outdoor 220 kV cable terminations at variable heights without compromising quality and safety. This paper/presentation will act as a guide for helping power engineers to build underground Transmission network in crammed cities of developing countries.
