On Site Dissolved Gas Analysis for Transformer Condition Assessment. Robin Watson - Kelman UK Karl Smith - Kelman Africa Henk Fourie - Kelman Africa

Transcription

1 On Site Dissolved Gas Analysis for Transformer Condition Assessment Robin Watson - Kelman UK Karl Smith - Kelman Africa Henk Fourie - Kelman Africa

2 Catastrophic Failure of Transformers

3 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

4 Dissolved Gas Analysis - DGA Most utilities use DGA to assess transformer condition Limited sampling of larger transformers with suspected issues This approach does not identify developing faults Some have a scheduled DGA program (eg annually) Tap Changer condition is also important Transformers & LTC s mostly sampled annually More critical transformers (GSU s and large system autos) sampled quarterly Most utilities would do more than 5000 samples per year

5 However there are difficulties Large distances to the lab Delays up to 2 weeks for standard samples Even critical rushed samples can take many hours Loss of transformer can cause significant loss of revenue

6 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

7 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.

8 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.

9 DGA Target Gas IR absorption spectra

10 Overall system used for Transport X

11 Overall system used for Transport X

12 Beta Trials: TXU and Alabama Power Randy Cox TXU Electric Delivery (shown here with colleague Tracy Nolan) Danny Bates Alabama Power

13 Laboratory Investigations Laboratory created large number of identical oil samples of known concentration Ran samples through 3 different GCs and Transport X Performed by Alabama Power personnel, September to November 2003 Gases shown separately for clarity Compares GC and Transport X for amplitude and variability

14 Comparison with GC CH4 C2H6 CO ppm Test Number Theoretical Concentration GC Readings GC Average Transport prototype Transport pre-prod ppm Test Number Theoretical Concentration GC Readings GC Average Transport prototype Transport pre-prod ppm Test number Theoretical Concentration GC Readings GC Average Transport prototype Transport pre-prod C2H4 C2H2 CO ppm Theoretical Concentration GC Readings GC Average Transport prototype Transport pre-prod ppm Theoretical Concentration GC Readings GC Average Transport prototype Transport pre-prod ppm Theoretical Concentration GC readings GC Average Transport prototype Transport preprod Test Number Test Number Test number

15 Analysis of Laboratory Tests Spread of Transport X results smaller than GC results indicates better repeatability Accuracy of Transport X at least as good as GCs often better However: Not conclusive tests Small number of tests Only tested at one concentration SO WE CARRIED OUT SOME FIELD TESTS

16 Field Tests to Compare Transport X results to GCs Many samples taken in US and in Europe Main 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.

17 Field Test results

18 Field Test Results (cont) Ethane Scatter CO Scatter CO2 Scatter Transport-10 ppm Ethane X=Y Linear (Ethane) Transport-10 ppm CO X=Y Linear (CO) Transport-10 ppm CO2 X=Y Linear (CO2) Various LAB ppm Various LAB ppm Various LAB ppm

19 Analysis of Field Testing Despite differing gas extraction and analysis techniques, overall correlation and linearity are excellent for all gases Remarkably low scatter for Methane, Ethane, Ethylene and Acetylene Slightly larger spread for CO and CO2 Hydrogen exhibits excellent linearity, but more mid-range data points required to test scatter

20 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.

21 Field Application Complements current DGA program Primarily for confirmation & rush samples Easy 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)

22 Developments Software support PC software for record download and storage TOA compatibility Embedded diagnosis algorithms Key Gas; Rogers Ratios; Duval s Triangle; Settable Caution & Warning thresholds Moisture measurement ON-Line DGA!

23 Embedded Diagnostic Tools

24 Testing at Cahora Bassa in Mozambique

25 Transfix On-Line DGA Uses same core technology Same Beta Test sites (TXU and Alabama) Adopted by many other worldwide utilities No consumables 8 gases + moisture Extensive Alarm options Remote and Local comms options Hourly sampling real-time DGA

26 Transfix On-Line DGA May 04 Transfix design review at Kelman with Danny Bates, Dr. Colin McIlroy & Robin Watson (engineering prototype in background)

27 Transfix Beta Test Sites

28 Transfix Alabama Installation Installed early November 04 very simple New LTC chosen for Beta Test See more action in a short period of time Resistive-type LTC small gassing per tap change Simulate developing fault on transformer Results remotely downloaded into TransCom

29 Transfix Alabama Installation

30 Conclusions DGA front line tool for transformer monitoring Transport X reliable DGA tool Meets real industry needs helps save $ s! On-line DGA of real interest for critical equipment Transfix has taken the market by storm and in Africa alone more than 50 units are installed.

31 Thank you. Any Questions?