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Overview & Benefits of Thermographic Inspection. SWEDE Conference Michael Navarro May 2007. WHAT IS THERMOGRAPHY?.

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overview benefits of thermographic inspection

Overview & Benefits ofThermographic Inspection

SWEDE Conference

Michael Navarro

May 2007

what is thermography
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.
benefits of thermographic inspections
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
recommendations for targeted inspection
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
recommendations for targeted inspection cont
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
oncor electric delivery s history
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
oncor electric delivery s history cont
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
oncor electric delivery s history cont8
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
when to perform thermographic inspections
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
criteria for determining the priority rating for repair
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)
what criteria determines the priority rating for repair
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
benefits
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
examples

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

examples cont
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

examples cont21
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

slide22

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

slide23

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

slide24

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

slide25

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

examples cont26
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

examples cont27
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

slide29

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

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