Press Releases & Publications

Sciene Daily: Leak Detectives

Science Daily — UPTON, NY - A novel method for finding dielectric fluid leaks in underground high-voltage electric cables protects the environment and prevents street excavations, while saving utilities time and money, according to a new study.

The approach has already been successfully used to pinpoint leak sin power lines contained in fluid-filled pipes under New York City's streets. It may also be potentially useful for finding problems in oil pipelines.

And, say researchers from the U.S. Department of Energy'sBrookhaven National Laboratory, the Consolidated Edison Company of New YorkInc. (Con Edison) and the Electric Power Research Institute, the method is much more efficient and effective than others in use.

The team describes the method in a paper in the currentTransactions on Power Delivery, published by the Institute of Electrical and Electronics Engineers.

PFT - Non-Intrusive Oil Filled Cable Leak Location

Use of Perfluorocarbon Tracers (PFT) in Self Contained Fluid Filled Cable Oil Leak Location.

 Authors:

Mike Fairhurst - National Grid Warwick England – mike.fairhurst@uk.ngrid.com

Patrick Keelan – PFT Technology LLC, New York, USA – patrick@pfttech.com

ABSTRACT

Oil leak location from buried cables is a critical step in addressing oil loss to the environment. A number of technologies have been applied to the problem with, to date, limited success. Recently developments have centered upon the use of tracers injected into the cable oil medium which when released into the soil will release a specific tracer gas that can be readily detected from above ground and does not require circuit outages. Outages are only required do effect repairs thereby reducing the overall outage time to locate and repair by approximately two thirds, thus improving system reliability and efficiency.

KEYWORDS

PFT, Freezing, Bar Holing, Tracer, PerFluorocarbon

INTRODUCTION

Self contained fluid filled cable technology is a mature, robust and reliable HV cable system that has been deployed in most major cities and towns around the world for many years. In recent times the deployment and installation of oil filled cable has declined, with the majority of new installations now using XLPE solid insulated cables. However due the high capital replacement cost, and with limited access to roads and streets in our major towns, it is anticipated that fluid filled technology will continue to be in service for many years to come.

Transmission Tests New Technology for Cable Leak Detection

(From the March/April 2005 issue of Network USA, National Grid’s newspaper for U. S.employees)

National Grid is assessing the use of tracer gas technology for finding fluid leaks in underground high-voltage transmission lines. This technique has the potential to reduce the environmental impact of leaks by speeding up the leak locating process.

Many underground transmission cables are insulated with a dielectric fluid, which is similar to mineral oil, and is pressurized at between one and 200 pounds per square inch (psi), depending on the cable type. Corrosion or mechanical fatigue of the cable sheath or pipe can result in fluid leaks. Leaks put the cable at risk of electrical failure, and can also release dielectric fluid to the environment. Since the cables are buried, locating the leak can be a time-consuming and difficult process.

Tracer technology increases infrastructure lifetime, saves money, protects the environment…

VERSAILLES, France –(June 20, 2011)– PFT Technology LLC, a global company specializing in leak detection services for fluid-filled cables used in high-voltage electric power transmission, today announced the success of its partnership with the UK’s National Grid, one of the largest investor-owned energy companies in the world. The partnership began in 2005 and since then has reduced the utility’s cable repair outage times by more than two-thirds, while also reducing cable dielectric fluid loss by more than 50 percent in the last three years. By employing its innovative, non-invasive dielectric fluid detection technology, PFT Technology (PFTtech) has helped National Grid significantly improve service reliability while reducing costs, road closures, service interruptions, and environmental impact. The results of the program were presented in a paper at Jicable 2011, the utility industry’s leading technical conference on insulated power cables, held in Versailles, France from June 19 – 23.

High voltage underground cables are typically filled with dielectric fluid to provide electrical insulation, suppress corona and arcing, and in some cases to serve as a coolant. The dielectric fluid is pressurized to prevent gases from forming inside the cable, which can cause catastrophic failure. When leaks occur, they are difficult to locate and expensive to repair, usually requiring major excavations and power outages.

Non-Intrusive Oil-Filled Cable Leak Location: Use of Perfluorocarbon Tracers increases infrastructure lifetime, saves money, protects the environment

By Mike Fairhurst, National Grid, Warwick, England

Self-contained, fluid-filled cable systems are mature, robust and reliable HV technology that has been deployed in most major cities and towns around the world for many years. In recent times the deployment and installation of oil-filled cable has declined, with the majority of new installations now using XLPE solid insulated cables. However, due the high capital replacement cost, and with limited access to roads and streets in our major towns, it is anticipated that fluid-filled technology will continue to be in service for many years to come.

High voltage underground cables are typically filled with dielectric fluid to provide electrical insulation, suppress corona and arcing, and in some cases to serve as a coolant. The dielectric fluid is pressurized to prevent gases from forming inside the cable, which can cause catastrophic failure. When leaks occur, they are difficult to locate and expensive to repair, usually requiring major excavations and power outages. Problems can occur with buried cables due to ground movement, deterioration, and third party strikes, which result in the leakage and loss of the insulating fluid. This leakage is often difficult to locate and repair when circuits need to be removed from service for the work to be done and can result in long outage periods. Leaks can range from a few litres per day to many litres an hour, having an effect on the local environment, causing breeches in national and local environmental legislation and exposing utilities to financial penalties and possible loss of reputation.