Product category:
Cabling, Conduit, Accessories and Signal Conditioning
News Release from: ERA Technology
Edited by the Engineeringtalk Editorial
Team on 21 September 2001
Improve the reliability of power cables
Preview of a paper by Bob Dean, manager of electrical power at ERA Technology, at the conference the 'Managing electrical plant in oil, gas and petrochemical installations' next month
"Power cables often experience gradual degradation of their insulation as they age, leading to partial discharge activity which can develop into cable damage and eventual failure This is a particular concern in the energy industry where older offshore platforms and petrochemical works contain large numbers of power cables that are more than 20 years old", warns Bob Dean, manager of electrical power at ERA Technology
Dean will be presenting a paper at the 'Managing electrical plant in oil, gas and petrochemical installations' conference on 26 September 2001 outlining the principles of measuring and assessing partial discharge to reduce the risk of cable failure.
A power cable contains a number of conductors separated by electrical insulation.
An electrical discharge which does not bridge the gap between two conductors is known as a partial discharge.
Partial discharges occur at areas of high electrical stress such as voids in insulation, conducting particles within the insulation and sharp protrusions projecting into the insulation.
Although partial discharges do not cause immediate failure of the cable, there is energy released at the site of a partial discharge and this energy can cause long-term damage to the insulation leading eventually to failure.
Detecting discharge activity in power cables can help to avoid costly failures and to improve the overall reliability of a cable system.
"Traditionally it has not been normal practice to test installed power cables due to the disruption caused by de-energising a cable for an off-line test and the likelihood of damaging a cable during tests at above system voltage", explains Dean.
"However, recent developments have allowed the use of small solid state devices to monitor groups of cables for partial discharge activity.
This non-intrusive monitoring enables cables with discharge activity to be identified so that cable mapping can then be undertaken to determine where the activity is occurring.
Modern mapping techniques allow more cost effective and practical assessments of the selected cables.
Although the mapping is an intrusive method that must be applied off-line, it is extremely powerful as a technique for detecting the position of discharge activity along the length of the cable.
Therefore a combination of monitoring and mapping allows a proactive asset management strategy for ageing cables to be developed." The partial discharge monitoring and mapping techniques described in the paper provide a phased approach to the condition assessment of electrical power cables.
Dean's paper will be presented at the conference, organised by ERA Technology, in Aberdeen.
This one-day conference and exhibition is aimed at anyone involved with maintaining electrical plant in ageing installations.
It will explain how decisions can be reached on whether to maintain or replace equipment.
Focusing on practical advice, delegates will gain an insight into new and existing monitoring technologies, understand the impact of safety and environmental issues and receive advice on how to specify equipment and choose the right asset for the right job.
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