overview & benefits of thermographic inspection

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.


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

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.)

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

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.)

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 (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?

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

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?

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

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


Equipment Required to Support Thermography


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


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


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


Examples (Cont.)


Temperature of Hot Spot –118.4 degrees C – Air Break Switch Middle Phase

Temperature of Spot 1 –38.8 degrees C – Air Break Switch


OUTAGE OCCURRED PRIOR TO REPAIR INVOLVING 2398 CUSTOMERS FOR UP TO 1 HRS 1 MIN

TWO STAGE RESTORATION FOR 27,588 CUSTOMER MINUTES


79.6 degrees C

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


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


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


Examples (Cont.)


Temperature of Hot Spot – 66.5 degrees C – elbow connection

Temperature of Spot 1 – 39.3 degrees C – reference elbow connection


INDIRECT HOT SPOT – WHILE REPAIRING, THE ELBOW CRUMBLED IN THE HANDS OF THE WORKER

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


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.)


Temperature of Hot Spot – 59.6 degrees C – All Arresters

Temperature of Spot 1 – 27.3 degrees C – Primary Bushing


Examples (Cont.)


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


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


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.)


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


History - 2005 Identified “Anomalies”


Questions?

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