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Overview & Benefits of Thermographic Inspection
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Overview & Benefits of Thermographic Inspection

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  1. Overview & Benefits ofThermographic Inspection SWEDE Conference Michael Navarro May 2007

  2. WHAT IS THERMOGRAPHY? • Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength. • Infrared radiation is popularly known as heat, heat radiation, or “hot spots”. • Infrared radiation can be used to remotely determine the temperature of objects. This process is commonly called “Infrared” in the electric utility industry.

  3. Benefits of Thermographic Inspections • Proactive thermographic inspections on Transmission and Distribution systems have proven: • Improvement in our SAIDI and SAIFI metrics • Reduced equipment failures, resulting in less capital spend • Reduction in O&M spend as a result of less reactive restoration, usually during overtime hours. • Improved reliability, or more specifically, a reduction in outages has a positive impact on customer satisfaction

  4. Recommendations for Targeted Inspection • Transmission Substation and equipment inspection • Distribution feeder main line inspection that is accessible by vehicle • Arresters, air switches, voltage regulators, capacitor banks, connectors, fused disconnects, insulators, solid disconnects, transformers, regulators, reclosers, riser pole terminations • Major Equipment - Switchgear, three-phase transformers, auto transformers, automatic transfer equipment, walk in vaults. Manholes are not included because of OSHA requirements for working in manholes • Special Request/Event inspections • Sporting events, convention facilities, fairgrounds, and any televised event

  5. Recommendations for Targeted Inspection(Cont.) • Government Facilities, Hospitals, Water Supply • Emergency infrared inspections can be utilized as a trouble shooting tool • Additional component of the Infrared Inspections is a detailed report which includes: • Delta T or Ambient temperature • FLIR software and reporting tools • NETA (National Electrical Testing Association) priority rating criteria

  6. Oncor Electric Delivery’s History • 1970’s • Nitrogen cooled camera held out of truck window • 1993 • Oncor system wide central program established with a Technical Services group. • Infrared inspect 2700 feeders & 800 substations per year • 1999 - 2001 • EPRI Project

  7. Oncor Electric Delivery’s History (Cont.) • 2001 • Transmission began inspection of substations • Improved quality by inspecting 1/3 of feeders • Optimized methodology identifying “hot spots” • 2002 • Performance Based Inspection (10% Worst Performing Feeders) • Overhead and Underground Facilities inspected • 2003 • Performance Based Inspections produced a higher % of hot spots with a higher priority rating while scanning fewer feeders • Spot checking new terminations • Added portable cameras

  8. Oncor Electric Delivery’s History (Cont.) • 2004 • Performance Based Inspections continued and more Underground Distribution facilities targeted • 2005 • Performance Based Inspections increased (20% WPF) • Additional Underground Distribution facilities targeted • $500,000 for Infrared Inspections contracted outside of company • 2006 • Performance Based Inspections continue

  9. When to Perform Thermographic Inspections? • Thermographic Inspections can be performed year round • Delta T process for Infrared allows this by using temperature rise over reference equipment rather than rise over ambient • Winter peaking feeders can be targeted • High visibility on darker days helps to identify anomalies

  10. Criteria for Determining the Priority Rating for Repair • Consumers Affected • The estimated number of consumers that may be affected and the type of equipment affected is taken into consideration. By using this information and the temperature of the hot spot along with the Thermographer’s experienced- based knowledge, the anomaly will be rated. • Priority 1…..low priority • Priority 2…..low priority • Priority 3…..work as you can • Priority 4…..within 24 hours (high priority) • Priority 5…..repair immediately (safety or imminent outage)

  11. What Criteria Determines the Priority Rating For Repair? • Wind • If the wind is greater than 15 mph, it will reduce the temperature measured by half. Wind speed will be measured by using either an instrument located on the truck or by local weather forecast Load and Time • Load and Time • The Load and Time of day will help determine the probability that as the day progresses the load will increase and the temperature of the hot spot will also increase. The Thermographer will use experience based knowledge and available data to derive at the grading of this priority • Safety Concerns • If there is a Safety Concern the hot spot will then be considered as a Priority 5 – repair immediately

  12. Benefits • There are several benefits for performing Infrared Inspections on the electrical system. • Enhanced operational safety and reliability of the system • SAIDI/ SAIFI improvements • Increased material and equipment life, resulting in capital savings • Proactively identifies workmanship issues • Maintenance cost reduced by preventing unscheduled outages • The only predictive maintenance available (***) • Saves you money

  13. Equipment Required to Support Thermography

  14. Equipment Required to Support Thermography

  15. Equipment Required to Support Thermography

  16. Equipment Required to Support Thermography

  17. Equipment Required to Support Thermography

  18. Equipment Required to Support Thermography

  19. 212.5 degrees C Examples Temperature of Hot Spot –239.2 degrees C – Solid blade disconnect switch Temperature of Spot 1 –26.7 degrees C – Solid blade disconnect switch Delta T temperature – 212.5 degrees C – rise above reference OUTAGE OCCURRED PRIOR TO REPAIR INVOLVING 203 CUSTOMERS FOR 3 HRS 2 MIN FOR 36,945 CUST MIN INFRARED INSPECTION PERFORMED 5-11-05 AND EQUIPMENT FAILED 7-23-05

  20. Examples (Cont.) 54.2 degrees C Temperature of Hot Spot –86.3 degrees C – Solid blade disconnect switch pothead connection on 2 phases Temperature of Spot 1 –32.1 degrees C – Solid blade disconnect switch Delta T temperature – 54.2 degrees C – rise above reference OUTAGE OCCURRED PRIOR TO REPAIR INVOLVING 1590 CUSTOMERS FOR UP TO 2 HRS 52 MIN FOUR STAGE RESTORATION FOR 190,186 CUSTOMER MINUTES INFRARED INSPECTION PERFORMED 6-8-05 AND EQUIPMENT FAILED 7-14-05

  21. Examples (Cont.) 79.6 degrees C Temperature of Hot Spot –118.4 degrees C – Air Break Switch Middle Phase Temperature of Spot 1 –38.8 degrees C – Air Break Switch Delta T temperature – 79.6 degrees C – rise above reference OUTAGE OCCURRED PRIOR TO REPAIR INVOLVING 2398 CUSTOMERS FOR UP TO 1 HRS 1 MIN TWO STAGE RESTORATION FOR 27,588 CUSTOMER MINUTES INFRARED INSPECTION PERFORMED 6-27-05 AND EQUIPMENT FAILED 7-4-05

  22. Examples (Cont.) Temperature of Hot Spot – 53.1 degrees C – blade of switchgear Temperature of Spot 1 – 42.6 degrees C – reference blade of switchgear Delta T temperature – 10.5 degrees C – rise above reference

  23. Examples (Cont.) Temperature of Hot Spot – 81.5 degrees C – capacitor oil switch Temperature of White Arrow Spot – 41 degrees C – reference capacitor oil switch Delta T temperature – 40.5 degrees C – rise above reference

  24. Examples (Cont.) Temperature of Hot Spot – 142.5 degrees C – H squeeze connection Temperature of White Arrow Spot – 33.6 degrees C – reference H squeeze connection Delta T temperature – 108.9 degrees C – rise above reference

  25. Examples (Cont.) Temperature of Hot Spot – 66.5 degrees C – elbow connection Temperature of Spot 1 – 39.3 degrees C – reference elbow connection Delta T temperature – 27.2 degrees C – rise above reference INDIRECT HOT SPOT – WHILE REPAIRING, THE ELBOW CRUMBLED IN THE HANDS OF THE WORKER

  26. Examples (Cont.) Temperature of Hot Spot – 32.5 degrees C – All 3 terminations Temperature of Spot 1 – 27.7 degrees C – reference top of termination Delta T temperature – 4.8 degrees C – rise above reference HOT SPOTS THAT APPEAR TO BE WHERE THE SEMI-CON IS CUT TOO DEEP DURING PREPARATION IS ACTUALLY A TERMINATION APPLIED INCORRECTLY ALLOWING A VOID THAT CREATES PARTIAL DISCHARGE

  27. Examples (Cont.) Temperature of Hot Spot – 59.6 degrees C – All Arresters Temperature of Spot 1 – 27.3 degrees C – Primary Bushing Delta T temperature – 32.3 degrees C – rise above reference

  28. Total 696 1684 2061 2662 1549 History - Ranking of “Anomalies”

  29. Infrared Inspection Items • Equipment • 2002 Total • 2003 Total • 2004 Total • 2005 Total • 2006 Total • ATO • 0 • 4 • 1 • 2 • 1 • Air Break Switch • 138 • 178 • 212 • 230 • 139 • Arrester • 336 • 451 • 525 • 707 • 459 • Capacitor • 22 • 21 • 48 • 27 • 26 • Capacitor Oil Switch • 65 • 58 • 68 • 86 • 25 • Disconnect Switch • 211 • 284 • 362 • 329 • 199 • Fused Cutout • 173 • 152 • 215 • 248 • 169 • Insulator • 1 • 1 • 5 • 1 • 0 • Manhole • 0 • 2 • 0 • 0 • 0 • Meter CT - Primary • 6 • 4 • 7 • 4 • 2 • Pothead • 50 • 44 • 63 • 91 • 34 • Primary Feeder • 130 • 174 • 178 • 191 • 169 • Recloser • 13 • 12 • 13 • 10 • 15 • Regulator • 13 • 42 • 18 • 7 • 10 • Secondary and Services • 8 • 0 • 45 • 76 • 25 • Switchgear • 16 • 122 • 33 • 183 • 61 • Transformer • 75 • 133 • 184 • 188 • 87 • UG Terminations • 0 • 0 • 80 • 281 • 106 • Vacumn Switch • 0 • 3 • 1 • 0 • 0 • Weather heads • 3 • 2 • 3 • 1 • 0 • 1259 • 1687 • 2061 • 2662 • 1549 History - Identified “Anomalies” by Device

  30. History - Identified “Anomalies” by Device (Cont.)

  31. History - 2006 Identified “Anomalies”

  32. History - 2005 Identified “Anomalies”

  33. Questions?