oncor electric delivery overview & benefits of thermographic inspection swede conference michael...
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Oncor Electric Delivery
Overview & Benefits ofThermographic Inspection
SWEDE ConferenceMichael NavarroMay 2007
Oncor Electric Delivery 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.
Oncor Electric Delivery 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
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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
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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
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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
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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
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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
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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
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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)
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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
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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
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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
212.5 degrees C
Examples
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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
54.2 degrees C
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 (Cont.)
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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
79.6 degrees C
Examples (Cont.)
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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
Examples (Cont.)
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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
Examples (Cont.)
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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
Examples (Cont.)
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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 (Cont.)
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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 (Cont.)
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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
Examples (Cont.)
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History - Ranking of “Anomalies”
0
500
1000
1500
YEARLY PRIORITY TOTALS
2002 76 327 65 199 29
2003 113 798 696 72 5
2004 119 860 1048 34 0
2005 251 867 1474 70 0
2006 85 477 985 2 0
Priority 5
Priority
4Priority
3Priority
2Priority
1
696
1684
2061
2662
1549
Total
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History - Identified “Anomalies” by Device
15492662206116871259
01323Weather heads 00130Vacumn Switch
1062818000UG Terminations8718818413375Transformer 611833312216Switchgear25764508Secondary and Services107184213Regulator 1510131213Recloser
169191178174130Primary Feeder 3491634450Pothead 24746Meter CT - Primary 00020Manhole01511Insulator
169248215152173Fused Cutout 199329362284211Disconnect Switch 2586685865Capacitor Oil Switch 2627482122Capacitor
459707525451336Arrester 139230212178138Air Break Switch 12140ATO
2006 Total2005 Total 2004 Total 2003 Total2002 TotalEquipment
Infrared Inspection Items
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YEARLY COMPARISON - INFRARED INSPECTIONS
0
100
200
300
400
500
600
700
800
2002 Total (1259) 2003 Total (1684) 2004 Total (2061) 2005 Total (2662) 2006 Total (1549)
History - Identified “Anomalies” by Device (Cont.)
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History - 2006 Identified “Anomalies”
2006 INFRARED INSPECTION DATA
Vacumn Sw itch, 0
UG Terminations, 106
Transformer , 87
Sw itchgear, 61
Secondary and Services, 42Regulator , 10
Recloser , 15
Primary Feeder , 169
Pothead , 34
Meter CT - Primary , 2
Manhole, 0
Insulator , 0
Fused Cutout , 174
Disconnnect Sw itch , 199
Capacitor Oil Sw itch , 25Capacitor , 26
Weatherheads , 0
ATO, 1
Arrester459
Air Break Sw itch , 139
0 100 200 300 400 500
Air Break Sw itch
Arrester
ATO
Capacitor
Capacitor Oil Sw itch
Disconnnect Sw itch
Fused Cutout
Insulator
Manhole
Meter CT - Primary
Pothead
Primary Feeder
Recloser
Regulator
Secondary and Services
Sw itchgear
Transformer
UG Terminations
Vacumn Sw itch
Weatherheads