1. DIAGNOSIS AND FAULT FINDINGS ON POWER TRANSFORMERS Michael Krüger, OMICRON Austria

2. DIAGNOSIS AND FAULT FINDING ON POWER TRANSFORMERS
Diagnosis of Tranformer On-load Tap Changers
29 November 2006
DIAGNOSIS AND FAULT FINDING ON POWER TRANSFORMERS
Moisture Measurement in Power Transformers
Online Monitoring on Transformer Bushings
Partial Discharge Location on a Transformer
Paper 4 -

3. Analysis of the Water Content by Comparison to Model Results
Measurement
Laboratory Results
Water Content
Oil Conductivity
Comparison
Fitting X
Oil
XY-Model
Barriers
Spacers Y
Temperature
Moisture determination bases on a comparison of the dielectric properties of the real transformer to modelled dielectric properties. The model bases on laboratory measurements on pressboard samples (upper right photograph) and the conductivity of oil. Both are combined by the XY-model taking into account the geometry condition of the transformer and the insulation temperature. A fitting algorithm arranges the modelled dielectric properties in order to get a good agreement to the measured dielectric properties. The best fitting curve provides the moisture content and oil conductivity of the real transformer.
Here you can demonstrate how the software works using the link to C:\Program Files\OMICRON\DIRANA\Dirana.exe
Source: Weidmann

4. Diagnosis of Tranformer On-load Tap Changers
29 November 2006
Assessment Settings
Check box:
Variable calculated by software
Required:
Oil temperature
Optional:
Geometry XY
Oil conductivity
Only the insulation temperature is absolutely required, all other data will be calculated by the software. However, if e.g. the geometry data are known, they will improve the accuracy of water determination.
The insulation temperature should be the upper oil temperature taken from an oil sample (most reliable) or the upper build-in oil thermometer (less reliable). Unfortunately oil thermometers are often in a position not reflecting the "true" temperature.
Paper 4 -

5. Diagnosis of Tranformer On-load Tap Changers
29 November 2006
Before Assessment
The fitting algorithm works automatically and emphasizes the low frequency values. Since water is reflected especially by the low frequencies left of the hump, the fitting should be good especially in this range.
The moisture content is an average including paper and pressboard of the insulation structures measured, usually the HV-LV insulation.
The analyzed moisture content is then automatically assessed according to IEC60422 with a traffic light indicating the moisture levels.
Paper 4 -

6. Diagnosis of Tranformer On-load Tap Changers
29 November 2006
Moisture Assessment
The fitting algorithm works automatically and emphasizes the low frequency values. Since water is reflected especially by the low frequencies left of the hump, the fitting should be good especially in this range.
The moisture content is an average including paper and pressboard of the insulation structures measured, usually the HV-LV insulation.
The analyzed moisture content is then automatically assessed according to IEC60422 with a traffic light indicating the moisture levels.
Paper 4 -

7. Diagnosis of Tranformer On-load Tap Changers
29 November 2006
Before Assessment
The fitting algorithm works automatically and emphasizes the low frequency values. Since water is reflected especially by the low frequencies left of the hump, the fitting should be good especially in this range.
The moisture content is an average including paper and pressboard of the insulation structures measured, usually the HV-LV insulation.
The analyzed moisture content is then automatically assessed according to IEC60422 with a traffic light indicating the moisture levels.
Paper 4 -

8. Diagnosis of Tranformer On-load Tap Changers
29 November 2006
After Assessment
The fitting algorithm works automatically and emphasizes the low frequency values. Since water is reflected especially by the low frequencies left of the hump, the fitting should be good especially in this range.
The moisture content is an average including paper and pressboard of the insulation structures measured, usually the HV-LV insulation.
The analyzed moisture content is then automatically assessed according to IEC60422 with a traffic light indicating the moisture levels.
Paper 4 -

9. Diagnosis of Tranformer On-load Tap Changers
29 November 2006
FDS / PDC Measurement on a 130 MVA TR Tan Delta Tertiary Winding to Tank > 1%
130 MVA
230 / 115 / 48 kV
Year of manuf. 1967
Rubber membrane in the expansion vessel
Paper 4 -

10. FDS / PDC Measurement on a 130 MVA Transformer – Water Content Distribution1 2 3 4 5
Moisture in paper [%]
FDS HV-LV
Oilsample
Karl Fischer
mg/kg
(Oommen
equilibrium)
FDS LV- Tertiary
FDS Tertiary- Tank
Tertiary not in use
RH %
Average
FDS
1mHz-1kHz

11. FDS / PDC Measurement on a 130 MVA Transformer
Decision:
online drying

12. 130 MVA Transformer Online Drying
Diagnosis of Tranformer On-load Tap Changers
29 November 2006
130 MVA Transformer Online Drying
Paper 4 -

13. Water Content Before and After Drying
Diagnosis of Tranformer On-load Tap Changers
29 November 2006
Water Content Before and After Drying
CHL CLT CT
before drying after drying
Paper 4 -

14. DIAGNOSIS AND FAULT FINDING ON POWER TRANSFORMERS
Diagnosis of Tranformer On-load Tap Changers
29 November 2006
DIAGNOSIS AND FAULT FINDING ON POWER TRANSFORMERS
Moisture Measurement in Power Transformers
Online Monitoring on Transformer Bushings
Partial Discharge Location on a Transformer
Paper 4 -

15. Advantages and Disadvantages of Off- and Online Measurements

16. 3 Phase Currents Sum - Comparison of the Same Phase
Patric Picher, Claude Rajotte, Denis Nadeau “Integration of New Transformer Monitoring
Technologies into a Modern IT Infrastructure”, TechCon Asia-Pazific 2011

17. Voltage Transformer as Reference

18. Bushing-Monitoring-System Montrano

19. 220kV Transformer with Monitoring-System

20. Monitoring-System Montrano
4 Cannels for Bushings + UHF
3 Channels for VT‘s R, S, T

21. Bushing Adapter

22. UHF Sensor

23. Voltage Transformers as Reference

24. WEB User Interface Montrano
28/11/2006
WEB User Interface Montrano

25. PD Values and Patters January
28/11/2006
PD Values and Patters January

26. Dielectric Dissipation Factor (Tan Delta) January
28/11/2006
Dielectric Dissipation Factor (Tan Delta) January

27. Transient Over-Voltages Inrush
28/11/2006
Transient Over-Voltages Inrush

28. Automatic Reclosure Phase L2 (blue)
28/11/2006
Automatic Reclosure Phase L2 (blue)

29. DIAGNOSIS AND FAULT FINDING ON POWER TRANSFORMERS
Diagnosis of Tranformer On-load Tap Changers
29 November 2006
DIAGNOSIS AND FAULT FINDING ON POWER TRANSFORMERS
Moisture Measurement in Power Transformers
Online Monitoring on Transformers
Partial Discharge Location on a Transformer
Paper 4 -

30. 28/11/2006
Gas Monitoring System Increase of H2 from 900 to 2000 ppm within 𝟐 𝟏 𝟐 Month

31. PD Measurement on the 220kV Bushing Phase V
28/11/2006
PD Measurement on the 220kV Bushing Phase V
June 25 with Montrano July 29 with MPD 600

32. 28/11/2006
PD Measurement with 9 synchronous Channels 220kV: U, V, W, N kV: U, V, W, N UHF

33. PD Measurement with UHF Probe
28/11/2006
PD Measurement with UHF Probe

34. Ultrasonic PD Measurement with PDL 600
28/11/2006
Ultrasonic PD Measurement with PDL 600

35. Search for the Best Microphone Position
28/11/2006
Search for the Best Microphone Position
PD Measurement Instrument
MPD 600
Ultrasonic
Microphone
Ultrasonic Receiver
Headphone

36. Search for the Best Microphone Position
28/11/2006
Search for the Best Microphone Position
Ultrasonic Receiver
MPD 600

37. Acoustic PD Location with PDL 600
28/11/2006
Acoustic PD Location with PDL 600

38. Acoustic PD Location with PDL 600
28/11/2006
Acoustic PD Location with PDL 600

39. Acoustic PD Location with PDL 600
28/11/2006
Acoustic PD Location with PDL 600

40. Deposit on the Surface of the 220kV Bushings
28/11/2006
Deposit on the Surface of the 220kV Bushings

41. Fault Finding at the Leads to the Bushings
28/11/2006
Fault Finding at the Leads to the Bushings

42. Fault Finding at the Leads to the Bushings
28/11/2006
Fault Finding at the Leads to the Bushings

43. Fault Finding at the press plates
28/11/2006
Fault Finding at the press plates

44.
Questions and Remarks?