Transmission Underground Cables
Both fluid-filled and XLPE High Voltage Underground cables are an essential part of many urban transmission systems. While they offer a number of distinct advantages in certain environments, they are expensive to maintain and replace. Adding to these maintenance costs, many fluid-filled installations (self-contained and Pipe Type) have been in operation since the early twentieth century, and a great number of these systems are being operated outside their original design parameters. Additionally, demographic shifts leading to retirement and voluntary departures in the electrical utility industry have resulted in a decrease in technical knowledge and expertise in the area.
The objective of the Transmission Underground Cables Interest Group (TUCIG) is to provide a forum for the exchange of information on cable asset management and to establish and promote techniques and tools for improving the management of fluid-filled and XLPE High Voltage underground cable systems. The group’s current emphasis is on the development of a ranking system for weigh factors used in the health assessment of cables, with the ultimate goal of establishing maintenance priorities while taking budget concerns into account.
Topics and Issues:
Development of an Asset Health Index Model
- Determination of the major contributing factors required to assess the health of aging cable systems (e.g. an understanding of different components’ aging processes, the determination of appropriate diagnostic tests and factors that affect life expectancy)
- Development of a mathematical Asset Health Index Model – an algorithm based on the major contributing factors
- Ranking of the results to prioritize alternative projects
Preventative and corrective maintenance
- Best in class practices for inspection frequency and procedures
- Emergency response plan for major incidents and/or failures
- Mutual aid agreement between participating utilities
- Methods and equipment for non-destructive testing
- Guidelines for entering an energized manhole for maintenance inspection
- Data collection automation to facilitate a real-time health index
- Reliability Centered Maintenance
Strategies for Life Cycle Asset Management
- Planning and decision making methodology to optimize spending allocation for maintenance and refurbishment or replacement projects
- Tools for evaluating residual life of cable systems
- Strategies for life extension of existing plant infrastructure
- End-of-life criteria
Assessment of available technologies and practices for line rating and condition monitoring systems
- Guide for application of Distributed Temperature Sensors (DTS) for real time rating and condition monitoring
- Assessment and acceptance criteria for Dissolved Gas Analysis (DGA) results.
- Continuous online monitoring techniques to replace manual processes
- Eliminate the need for jacket tests on self-contained jacketed cables with sheath bonding by utilizing sheath current monitoring equipment
Means of minimizing environmental impact
- Guidelines for managing oil leaks
- Spill containment systems
- Procedure for identifying and locating oil leaks
