Cable Life Extension: Managing lifecycle performance of T&D cable systems

Megger 2022-04-05 00:00:00

Knowledge is powerful. Understanding every aspect of the electricity network, from generation and transmission to distribution and consumption, is what it takes to be recognized as a world leader in designing and providing assessment and diagnostic solutions for electrical network assets and their connected equipment. Megger's commitment to innovation with new product development being a key business driver has allowed the company to extend its portfolio of products into managing aging underground cable system assets to improve grid reliability at a lower cost than replacement. Megger's solution offers utilities and testing clients the cable assessment and diagnostic technology to manage a utility wide Cable Life Extension Program (CLEP) that will certify and extend the life of aged underground system infrastructure to "like-new" status. As part of a CLEP program, aged underground cables are ensured to work correctly and without fault under normal operating conditions for many years to come and, in many cases, beyond the cable system design life. Megger currently works with many of the top Investor-Owned Utilities (IOUs), municipals and electric cooperatives across the US that may benefit stakeholders and ratepayers alike by significantly reducing underground cable replacement budgets by up to 75%. This may effectively contribute to a lowered rate base while improving major reliability metrics in aged end-of-life assets.

The need to upgrade aging infrastructure has been cited by many industry analysts as one of the major factors affecting power reliability, with grid hardening and modernization at the forefront of concerns for many electric utility companies. Using Megger's cable certification process, utility asset managers can make informed cable health decisions regarding grid reliability instead of replacing underground cable systems reactively upon failure using unplanned expenditures. It has been recognized in the industry that more than 60% of aged cable systems (those 25+ years in age) are shown to meet the performance requirements of newly installed systems. A decade ago, the Federal Energy Regulatory Commission ("FERC") ruled that electric utility companies may use capital funds as a betterment process to rejuvenate or assess aged underground cable assets giving them an option to utilize Megger's cable assessment and diagnostic technology to proactively extend their capital budgets by using funds typically earmarked for underground cable replacement. The Megger assessment process can expand capital reach 2, 3 or even 4 times, while achieving the same reliability impact as that of wholesale cable replacement.

Cable Diagnostics
A cable assessment program encompasses high voltage assessment and diagnostics. The key objective is to increase system reliability by preemptively identifying defects in the cable that might result in its eventual failure. Cable problems can be generally characterized as local or global (e.g., those that affect the entire cable span). Local problems include defects at terminations, joints and in the insulation itself. A local insulation problem may be caused by a cable weak spot but can also be man-made as many defects found in aged systems today can be traced back to poor workmanship practices during installation. In addition, it is also possible that insulation may also be defective on a global scale, such as general age-related degradation where water trees become prominent throughout extruded type cables, leading to compromised insulation dielectric strength.

Cable and accessory manufacturers have, for a long time, believed that a catalyst of cable system failure is a phenomenon associated with partial discharge (PD). Consequently, manufacturers, have quality control tested newly manufactured components for PD activity as a standard operating procedure since the 1960s.  These manufacturers perform highly sensitive partial discharge measurements in multi-million dollar shielded laboratories and replicating these test conditions with limited noise levels and high sensitivity had proven impractical in a field-testing environment until recently. Megger's portfolio of cable assessment and diagnostic equipment provides innovative technology to field assess both aged and newly commissioned systems.  The results delivered highlight defects in the in installed systems in the same way as the manufactures quality control checks do during the manufacturing process.  This allows utilities to make health, risk and impact decisions on installed cable systems to determine a robust rehabilitation plan, saving capital replacement outlay and in turn, avoided maintenance costs.

In summary
Megger's Cable Test and Diagnostic equipment enables US electric utility companies to optimize their approach to meeting the reliability challenges faced with managing aged underground infrastructure. Utility asset managers were once faced with a dichotomy when dealing with these assets; choosing to either reactively replace complete loops or spans based on age and failure rate (which is cost prohibitive, has a minimal impact on reliability metrics, and is an ineffective use of funds); or to repair and replace these systems using unplanned capital and O&M budgets. Today, a far more comprehensive yet cost effective and proactive approach can be considered, to extend the overall electric cable system's useful life beyond the original estimated service life. Efficient rehabilitation of underground cable systems, through measurement of cable system and component integrity, will ultimately save electric utility companies billions of dollars in replacement costs, help reduce power outages, offset price increases, and ultimately benefit electric consumers. 

Going to IEEE PES in New Orleans, Louisiana in April?
Visit Megger at booth 8529 to see Megger's line-up of cable assessment and diagnostic equipment and determine if a Cable Life Extension Program is the right asset performance management program to oversee your underground assets and maximize operational life.

For additional information on Megger's cable fault, testing and diagnostics line of products please visit,-test-and-diagnostics.

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