Robin Watson - Kelman UK Karl Smith - Metering.com SITE DISSOLVED G… · Robin Watson - Kelman UK...
Transcript of Robin Watson - Kelman UK Karl Smith - Metering.com SITE DISSOLVED G… · Robin Watson - Kelman UK...
On Site Dissolved Gas Analysis for Transformer Condition Assessment
Robin Watson - Kelman UKKarl Smith - Kelman AfricaHenk Fourie - Kelman Africa
The state of the oil is the key
These gases are a clue to the heat sources in the oil
Also Carbon Monoxide and Carbon Dioxide to state of Paper Insulation
Dissolved Gas Analysis - DGA
Most utilities use DGA to assess transformer conditionLimited sampling of larger transformers with suspected issuesThis approach does not identify developing faultsSome have a scheduled DGA program (eg annually)Tap Changer condition is also important Transformers & LTC’s mostly sampled annuallyMore critical transformers (GSU’s and large system autos) sampled quarterlyMost utilities would do more than 5000 samples per year
However there are difficulties
Large distances to the labDelays up to 2 weeks for standard samplesEven critical rushed samples can take many hoursLoss of transformer can cause significant loss of revenue
Kelman saw this as an opportunity and joined up with 2 key customers to develop a new approach
• Room for improvement..?• Interested in new ideas• Often skeptical of new technology
- pie in the sky?• Reliable portable DGA in small box?
- is that possible?• The 2 customers agreed to Beta Test
Transport X- lab and field testing
Photo-Acoustic Spectroscopy:
Principle discovered in 1880s by Alexander Graham Bell.Infra Red radiation absorbed by gas.Each gas has an unique IR absorption spectrum.Level of absorption is proportional to gas concentration.
Photo-Acoustic Spectroscopy:
Absorbed IR radiation causes rise in temperature, hence rise in pressure.If the radiation is pulsed at an audible rate the resultant pressure wave can be detected by sensitive microphones.Technique capable of measuring accurate concentrations in a complex cocktail of compounds.
Beta Trials: TXU and Alabama Power
Danny Bates
Alabama Power
Randy Cox
TXU Electric Delivery(shown here with colleague Tracy Nolan)
Laboratory Investigations
Laboratory created large number of identical oil samples of known concentrationRan samples through 3 different GCs and Transport XPerformed by Alabama Power personnel, September to November 2003Gases shown separately for clarityCompares GC and Transport X for amplitude and variability
Comparison with GCC2H6
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1 2 3 4 5 6 7 8 9 10
Test Number
ppm
TheoreticalConcentration
GC Readings
GC Average
Transport prototype
Transport pre-prod
CH4
8 9 10
umber
TheoreticalConcentration
GC Readings
GC Average
Transport prototype
Transport pre-prod
CO2
0
50
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1 2 3 4 5 6 7 8 9 10
Test number
ppm
TheoreticalConcentrationGC Readings
GC Average
TransportprototypeTransport pre-prod
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30
1 2 3 4 5 6 7
Test N
ppm
CO
0
5
10
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25
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35
1 2 3 4 5 6 7 8 9 10
Test numberpp
m
TheoreticalConcentrationGC readings
GC Average
TransportprototypeTransport pre-prod
C2H4
0
2
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1 2 3 4 5 6 7 8 9 10
Test Number
ppm
TheoreticalConcentration
GC Readings
GC Average
Transport prototype
Transport pre-prod
C2H2
0
0.5
1
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2.5
1 2 3 4 5 6 7 8 9 10
Test Number
ppm
TheoreticalConcentration
GC Readings
GC Average
Transport prototype
Transport pre-prod
Analysis of Laboratory Tests
Spread of Transport X results smaller than GC results –indicates better repeatabilityAccuracy of Transport X at least as good as GCs – often better
However:Not conclusive testsSmall number of testsOnly tested at one concentrationSO WE CARRIED OUT SOME FIELD TESTS
Field Tests to Compare Transport X results to GCs
Many samples taken in US and in EuropeMain tanks, LTCs, CBs and bushings tested.Wide range of conditions – temperature and humidity Data incorporates different labs, different Transport X units, different sampling techniques, and different electrical equipment etc.
Field Test Results (cont)
CO2 Scatter
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Various LAB ppm
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ppm
CO2X=YLinear (CO2)
Ethane Scatter
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0 100 200 300 400 500Various LAB ppm
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t-10
ppm
EthaneX=YLinear (Ethane)
CO Scatter
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0 200 400 600 800
Various LAB ppm
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t-10
ppm
COX=YLinear (CO)
Analysis of Field Testing
Despite differing gas extraction and analysis techniques, overall correlation and linearity are excellent for all gasesRemarkably low scatter for Methane, Ethane, Ethylene and Acetylene Slightly larger spread for CO and CO2Hydrogen exhibits excellent linearity, but more mid-range data points required to test scatter
Worldwide
TRANSPORT X tested & adopted worldwide
UK, Ireland, Germany, Norway, Denmark, Sweden, Iceland, Croatia, Russia, Slovakia, Israel, Saudi Arabia, South Africa, Namibia, Kenya, Morocco, USA, Canada, Mexico, China, Mongolia, Korea, Singapore, Malaysia, Philippines, Indonesia, and growing by the day.
Field Application
Complements current DGA program– Primarily for confirmation & rush
samplesEasy to use – little expertise required
If you can take good sample, you can use Transport X
• Reliable portable DGA...?– ‘…given us the upper hand’ (D. Bates)
Developments
Software supportPC software for record download and storageTOA compatibilityEmbedded diagnosis algorithms
Key Gas; Rogers’ Ratios; Duval’s Triangle; Settable Caution & Warning thresholds
Moisture measurementON-Line DGA!
Transfix – On-Line DGA
Uses same core technologySame Beta Test sites (TXU and Alabama)Adopted by many other worldwide utilitiesNo consumables8 gases + moistureExtensive Alarm optionsRemote and Local comms optionsHourly sampling – real-time DGA
Transfix – On-Line DGA
May ’04Transfix design review at Kelman withDanny Bates, Dr. Colin McIlroy & Robin Watson
(engineering prototype in background)
Transfix – Alabama Installation
Installed early November ’04 – very simpleNew LTC chosen for Beta Test – See more ‘action’ in a short period of time
Resistive-type LTC – small gassing per tap changeSimulate developing fault on transformer
Results remotely downloaded into TransCom®
Conclusions
DGA front line tool for transformer monitoringTransport X reliable DGA toolMeets real industry needs – helps save $’s!
On-line DGA of real interest for critical equipmentTransfix – has taken the market by storm and in Africa alone more than 50 units are installed.