cable aging assessment and condition monitoring with...
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Cable Aging Assessment and ConditionMonitoring with LIRA
Paolo F. FantoniOECD Halden Reactor Project
Institutt for energiteknikkHalden, Norway
IEEE SC2 Meeting, Newport Beach, CA, 7-8 November 2006
2 December 2006
HRP Project on Cable AgingThe LIne Resonance Analysis (LIRA)
method• Based on frequency domain analysis of high
frequency resonance effects of unmatched transmission lines.
• Sensitive to small changes of wire electric parameters, mainly the insulation permittivity, that are a significant condition indicator of the cable state (thermal and radiation aging, humidity, insulation defects, mechanical damage).
• Possibility to detect and localize small insulation cracks, in spite of different structures (insulation type, geometry) and not-aging related effects.
2 December 2006
Electric parameters in a cable
2 December 2006
LIRA as a Condition Indicator
Analysis of the line input impedance amplitude/phase provides:
• Accurate estimation of the phase velocity, correlated to the global cable condition
• Detection and localisation of one/many hot spots along the cable
2 December 2006
Hot spot detection in LIRA
2 December 2006
Global Condition Indication
• Phase Velocity (PV) in LIRA is estimated with 4 precision digits (0.XXXX). PV is a decreasing function of global insulation degradation.
• PV can be correlated to any other accepted Condition Indicator (ie EAB), for condition assessment and residual life estimation (EPRI tests, November 2006)
Velocity ratio vs. capacitance
7400
7500
7600
7700
7800
7900
8000
56 57 58 59 60 61
Capacitance (pF/m)
Vel
. rat
io *
E+4
2 December 2006
Wirescan, implementing the LIRA engine
• 3 SW modules:• Generator controller• Analyzer• Simulator
• 3 HW modules:• AWG Generator (NI-PXI)• DSO Digitizer (NI-PXI)• Modulator (Wirescan)
2 December 2006
Wirescan beta version (Aug. 2006)
2 December 2006
Wirescan in a field experiment
2 December 2006
Projects/Experiments
• EPRI (2005 – 2006)• Norsk Hydro (2005)• NKS, Ringhals, Barseback (2005 2006)• PETROMAKS (NFR, Hydro, Shell, 2006-2008)• NEXANS, 2006
2 December 2006
EPRI Tests
• September 2005: preliminary, feasibility tests on Okonite and Rockbestos specimen
• May 2006: detection of cuts and gouges(EPR and XLPE)
• November 2006: local and bulk degradation. Effect of wet vs. dry
2 December 2006
EPRI Tests (September 2005)
• 10 EPR and XLPE specimens have been tested at EPRI, Charlotte, on September 15th and 16th
• The cable samples had passed bulk accelerated aging and local spots in different positions
• LIRA was used to identify both severity and position of the local thermal spots and the bulk aging.
2 December 2006
EPRI Experiment (May 2006)
• EPR and XLPE I&C cables from several vendors (Brand Rex, Rockbestos,Dekoron, Okonite) were tested for detection of cuts and gauges, both in dry and wet conditions.
• Initial measurements on good cables were taken. These cables will go through accelerated thermal aging in the period June-September 2006. New tests on these cable will be carried on in November, to evaluate the LIRA performance in assessing local and bulk thermal degradation.
2 December 2006
EPRI Experiment, May 2006
2 December 2006
XLPE Brand Rex. Cut (at 24m) down to the insulation, 2 wires, dry
2 December 2006
Specimen XBC1, LIRA spot detection
2 December 2006
XLPE Rockbestos. Gouge (at 24m) down to the insulation,2 wires, dry
2 December 2006
Specimen XRG1
2 December 2006
EPRI tests, May 2006, conclusions
• LIRA performed well in detecting hot spots in both Okonite and Rockbestos cables (September tests).
• The localization accuracy is lower than 0.5%.• Tests with cuts and gauges showed that LIRA can
detect mechanical defects in wet and dry conditions.• Reference measurements were taken with cables
that will be locally and globally aged (used in November 2006 tests)
2 December 2006
EPRI tests, November 2006
2 December 2006
Thermal hot spots at 8m (22.5m)
2 December 2006
Hot spots (22.5m), 4 aging times, EPR
EIL1: 216hrs at 150CEIL2: 479hrs at 150CEIL3: 527 hrs at 150CEIL4: 575 hrs a 150C
1m thermal agingAt 8m (22.5)
2 December 2006
Hot spots (22.5m), 4 aging times, XLPE
1m thermal agingAt 8m (22.5)
XRL1: 1002hrs at 150CXRL2: 1150hrs at 150CXRL3: 1300hrs at 150CXRL4: 1450hrs at 150C
2 December 2006
Hot spots, correlation with aging, EPR (BIW)
LIRA indication vs. aging, EPR
30.0
32.0
34.0
36.038.0
40.0
42.0
44.0
0 24.1 53.5 58.8 64.2Years at 80C
Nor
m d
B
2 December 2006
Hot spots, correlation with aging, XLPE (Rockbestos)
LIRA indicator vs. aging, XLPE
60.0
61.0
62.0
63.0
64.0
65.0
66.0
67.0
68.0
0 12.0 13.8 15.6 17.4Years at 100C
dB n
orm
To be evaluated
2 December 2006
Tests on 5kV, EPR, aged and wet
2 December 2006
5kV EPR cable (12B), aged, wet
2 December 2006
5kV EPR cable (15A), aged, wet
2 December 2006
Bulk aging tests
2 December 2006
Bulk aging, XLPEPhase Velocity Ratio vs. aging, XLPE (Rockbestos)
0
584
800
0.61
0.615
0.62
0.625
0.63
0.635
0.64
0.645
0.65
0 100 200 300 400 500 600 700 800 900
Time at 150C (hr)
Phas
e Ve
loci
ty R
a
2 December 2006
Wet vs. dry, EPR
No change in VR
Hot spot at 22.5m
2 December 2006
Wet vs. dry, XLPE
Much lower VR in wet conditions
Hot spot at 22.5m
2 December 2006
Ringhals experiment, June 2006
2 December 2006
Ringhals Experiment
Low voltage, 140m triaxial cable with PVC insulation, 20-25 years aging condition.
Verify that cable extraction and reinsertion does not cause jacket/insulation damage
Line impedance signature
2 December 2006
First on-site test
• Top signature: analysis of the 140m cable with penetration at 105m
• Bottom signatures: analysis of the 105m disconnected cable (at the penetration), before and after relocation
No detectable damage as a consequence of cable movement
2 December 2006
Recent Reports on Cable Aging
• IAEA TECDOC 1188, December 2000, Assessment and management of ageing of major nuclear power plant components important to safety
• Report of the IAGE Task Group on Wire System Aging (NEA). Final report released August 2004 ( NEA/CSNI/R(2004)12 ).
• State-of-the-art report ( HWR-746 ) released April 2004 (Halden Reactor Project Report).
• Workshop on Wire System Assessment and Condition Monitoring, Zurzach (CH), October 29-30, 2004 (HWR-787)
• LIRA Technology (HWR-788), October 2005