Check this page periodically to learn about the Presentations scheduled for the Fall meeting.
Please Note: This is a only a listing of the
presentations and
DOES NOT IMPLY THE ORDER IN WHICH THEY WILL BE PRESENTED.
In addition, a writing/editing volunteer group will be identified. This group should be willing to meet after the Fall ICC meeting but at least 2 months before the Spring ICC meeting to finalize the writing of the document.
The individuals who sent written comments about the draft and any other participant who wants to discuss these or additional issues are invited to send a request to the Chair/Vice-Chair of the Working Group by October 16, 2000 specifying the subject of the discussion. Every effort will be made to schedule 5-10 minutes per individual for the discussion. Email: Matt Mashikian: mashikian@aol.com Willem Boone: wboone@comcat.com
The comments have been compiled into a single document, along with a recent article by Steve Boggs and John Densley on PD measurements. Please read the comments before the meeting to make our time as productive as possible.
It is known that PD detection and localisation is a useful tool for the identification of degradation processes in the insulation material of cable systems. This presentation discusses on the basis of typical field experiences the ageing problems in the medium voltage power cable networks. In particular, using advanced PD diagnosis at oscillating wave voltages (in the range of few hundreds of Hz) important systematic information is evaluated: PD inception/extinction voltages, PD amplitude, PD pattern and PD location (cable or accessories). As a result evaluation criteria and knowledge rules for degradation processes in the different insulation systems can be derived to support condition assessment of the cable system.
The common method based on the principles of reflectrometry has recently been extended by introducing the so-called multi terminal synchronized diagnostic method. By using this diagnostic method, branched cable circuits and cables of long length (over 15,000 ft) can be diagnosed successfully.
In this presentation after an introduction about different maintenance philosophies, the technical principles of reflectrometry based testing and multi terminal synchronized testing will be explained and typical results of interpretation of the measured information and the conversion into practical recommendations with regard to maintenance actions, like repair or exchange of components. Finally a few cost/benefit evaluations concerning diagnostic testing services and related actions, will be dealt with.
Therefore, also the demand for diagnosis of power cables is increasing. For partial discharge (PD) testing of power cables, the cable has to be energized with alternating voltages equal or above the operating voltage. As one can imagine, the high capacitive load makes the off-line testing of power cables difficult. Several approaches to overcome this problem exist. However they are always a trade-off, with some disadvantages. For partial discharge testing of the cable, we therefore developed a new, hybrid voltage shape and it’s generator.
It combines the advantages of:
The CDA system is used for testing medium voltage PILC, XLPE and EPR cables as well as mixed cable structures. A condition assessment of aged cables can be performed as well as PD tests for the commissioning of new cables.
The system is commercial available since four years. Built into a test van, it is in use at several utilities in America and Europe.
The new CDA waveform with its advantages and disadvantages will be
explained to the audience, followed by a description of the standard test procedure.
Several test results will be discussed. At last, an outlook of future developments will be
given.
Most of these insulation problems are accompanied by the presence of partial discharges. In particular, the presence of partial discharges can be described by PD inception/extinction voltages, PD amplitude and PD phase-resolved patterns. Performing PD diagnostics several aspects are of importance:
It is known, that to obtain a sensitive picture of discharging faults in power cables the PD should be ignited, detected and located at power frequencies which are comparable to operating conditions at 50 or 60 Hz. In this way realistic magnitudes in [pC]/[nC] and reproducible patterns of discharges in a power cable can be obtained.
In this contribution PD detection, measurement and analysis using oscillating wave test method is presented as new PD test procedure of medium voltage PILC and polymeric insulated cables. In particular PD inception conditions, PD magnitudes, PD phase-resolved patterns at slowly decaying voltages at different oscillating frequencies (50Hz....500Hz) as well as the PD-location mappings are compared for several insulation defects. In addition, based on systematic field experiences with
The general applicability of PD detection at oscillating voltages will be discussed.
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