Review of TADS Data for 2012

Voltage Class Name Metric

AC Transmission Outages - Failed

Protection System

Equipment

AC Transmission

Outages - Human Error

AC Transmission Outages - Failed AC Substation

Equipment

AC Transmission Outages - Failed

AC Circuit Equipment

AC Transmission

Outages - Lightning

AC Transmission

Outages - Contamination

AC Transmission

Outages - Foreign

Interference

Total

Element Availability Percentage

(APC)

Transmission System

Unavailability

AC Circuit 300-399 kV

Outages per Circuit 0.0262 0.0426 00.0589 0.0458 0.2013 0.0990 0.0607 0.7348 98.6192 1.3808

AC Circuit 300-399 kV

Outages per 100 miles per year 0.0804 0.1307 0.1809 0.1407 0.6333 0.3116 0.1910 2.3121

300-399 kV Jan-12 Dec-12

# Circuits 310 316

Circuit Miles 9845.6 10049.4

Multi-circuit Structure Miles 2755.3 2970.3

Automatic Outages

Circuit Data

Outage Information Count Duration (hrs)

Automatic 230 682.6

Non-Automatic 516 36295.1

Outage Data

Outage Information CountDuration

(hrs)

Two Elements 9 4.82

Three Elements 3 5.3

Four or More Elements 1 18.3

Multiple Element Automatic Outages

Fault Types Count % Count % Duration %No fault 4 2.67% 41 51.25% 259.67 38.04%P-P fault 1 0.67% 0 0.00% 0 0.00%P-G fault 134 89.33% 38 47.50% 422.9 61.96%P-P-G, 3P, or 3P-G fault 7 4.67% 1 1.25% 0.02 0.00%Unknown 4 2.67% 0 0.00% 0 0.00%Total 150 80 682.59

Momentary Sustained

Review of TADS Automatic Outage Data for 2012

7.3%

31.3%

15.3%10.7%

0.0%0.0%

1.3%

5.3%0.7%

0.7%

26.7%

0.7%

Momentary Outage Cause Weather, excluding lightning

Lightning

Contamination

Foreign Interference

Fire

Failed AC Substation Equipment

Failed Protection System Equipment

Failed AC Circuit Equipment

Power System Condition

Human Error

Unknown

Other

05

101520253035404550

Sustained Outages Momentary OutagesAutomatic Outages By Month

● Lightning, Contamination, and Unknown represent 73% of all momentary outages

● Momentary and Sustained automatic outages by month for 2012

Review of TADS Automatic Outage Data for 2012

2.5%

20.0%

10.0%

3.8%1.3%

22.5%

7.5%

7.5%

5.0%

15.0%

5.0% 0.0%

Sustained Outage Cause Weather, excluding lightning

Lightning

Contamination

Foreign Interference

Fire

Failed AC Substation Equipment

Failed Protection System Equipment

Failed AC Circuit Equipment

Power System Condition

Human Error

Unknown

Other

0.0%6.1%

0.0% 0.2%

2.8%

46.4%

2.9%

16.2%

21.3%

4.0%

0.1%0.0%

Sustained Outage DurationWeather, excluding lightning

Lightning

Contamination

Foreign Interference

Fire

Failed AC Substation Equipment

Failed Protection SystemEquipmentFailed AC Circuit Equipment

Power System Condition

Human Error

Unknown

Other

● Failed AC Substation Equipment represented 22% of sustained outage cause vs. 46% of sustained outage duration

● Failed AC Circuit Equipment represented 7% of sustained outage cause vs. 16% of sustained outage duration

Review of TADS Planned Outage Data for 2012

42482.2%

438.3%

40.8%

346.6%

81.6%

00.0%

30.6%

Planned & Operational Outage CauseMaintenance andConstruction3rd Party Request

Other Planned Outage

Emergency

System Voltage LimitMitigationSystem Operating LimitMitigationOther Operational Outage 29879.5

82%

1892.55%

258.51%

2354.756% 1270.75

4%0

0% 639.022%

Planned & Operational Outage Duration (Hours) Maintenance and

Construction3rd Party Request

Other Planned Outage

Emergency

System Voltage LimitMitigationSystem Operating LimitMitigationOther Operational Outage

0

10

20

30

40

50

60

70

80

Planned & Operational Outages by Month

0

1000

2000

3000

4000

5000

6000

7000

8000

Planned & Operational Outage Duration by Month (Hours)

Review of TADS Planned Outage Data for 2012

40.8%

10.2%

163.1% 23

4.5%

28455.0%

458.7%

14327.7%

Planned & Operational Outage Count by Duration

1-5 minutes

6-10 minutes

11-30 minutes

31-120 minutes

121 minutes to 24 hours

>24 hours to 48 hours

> 48 hours

● 55% of planned outage duration ranges from two to 24 hours

● 37% of planned outage duration is greater than 24 hours

TADS Comparison, 2011 vs 2012

2011 2012

Outage Information Count Duration (hrs) Count Duration (hrs)

Automatic 279 1908.6 230 682.6

Non-Automatic 787 46712.4 516 36295.1

2011 2012 2011 2012Voltage Class 300-399 kV 300-399 kV 300-399 kV 300-399 kV

Metric Outages/Number of circuits Outages/100 mi/year

AC Transmission Outages - Failed Protection System Equipment

0.0305 0.0262 0.0926 0.0804

AC Transmission Outages - Human Error0.0677 0.0426 0.2057 0.1307

AC Transmission Outages - Failed AC Substation Equipment

0.1320 0.0589 0.4011 0.1809

AC Transmission Outages - Failed AC Circuit Equipment

0.0508 0.0458 0.1543 0.1407

AC Transmission Outages - Lightning0.2067 0.2055 0.6376 0.6333

AC Transmission Outages - Contamination0.1667 0.1011 0.5142 0.3116

AC Transmission Outages - Foreign Interference0.0567 0.0620 0.1748 0.1910

Total 0.9300 0.7504 2.8694 2.3121

Element Availability Percentage (APC)98.0625 98.6192

Transmission System Unavailability1.9375 1.3808

TADS Comparison, 2010-2012

0

10

20

30

40

50

60

702010 2011 2012

Automatic Outages by Month

0

100

200

300

400

500

600

700

8002010 2011 2012

Automatic Outage Duration by Month (Hours)

0

20

40

60

80

100

120

1402010 2011 2012

Planned and Operational Outages by Month

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

100002010 2011 2012

Planned and Operational Outage Duration (Hours) by Month

TADS Comparison, 2008-2012

0

10

20

30

40

50

60

70

802008 2009 2010 2011 2012

Momentary Outages by Cause

0

5

10

15

20

25

302008 2009 2010 2011 2012

Sustained Outages by Cause

0

100

200

300

400

500

600

700

8002008 2009 2010 2011 2012

Sustained Outage Duration (Hours) by Cause

• April-May 2011 had higher than normal rate of contamination-related outages due to ongoing drought issues

• Sept 2011 had high sustained outage duration due to wildfires

Common Mode and Dependent Mode Outage Statistics2010-2012

• Dependent Mode outages (defined as an automatic outage of an element which occurred as a result of another outage)

• Common Mode outages (defined as one or more automatic outages with the same initiating cause and occur nearly simultaneously)

• In 2012, represented 6.0% of all momentary outages, 26.3% of all sustained outages (6.6% of sustained outage duration), and 13.0% of all automatic outages.

0.00%

1.00%

2.00%

3.00%

4.00%

5.00%

6.00%

7.00%

8.00%

Dependent ModeInitiating

Dependent Mode Common Mode Common ModeInitiating

2010 2011 2012Momentary Outage Modes Comparison

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

Dependent ModeInitiating

Dependent Mode Common Mode Common ModeInitiating

2010 2011 2012Sustained Outage Modes Comparison

91.89%

0.72%

4.30%3.10%

0.00%

Avg AC Circuit Momentary Automatic Outage Mode

Single Mode

Dependent ModeInitiating

Dependent Mode

Common Mode

Common Mode Initiating

66.67%

3.86%

25.61%

3.86%0.00%

Avg AC Circuit Sustained Automatic Outage Mode

Single Mode

Dependent ModeInitiating

Dependent Mode

Common Mode

Common Mode Initiating

NERC Adequate Level of Reliability (ALR) Metrics

2010 2011 2012

Metric Definition ERCOTMetric

NERCMetric

ERCOTMetric

NERC Metric

ERCOTMetric

NERCMetric

ALR6-11 Automatic Outages Initiated by Failed Protection Equipment

4.95% 6.26% 3.05% 5.55% 2.62% 5.07%

ALR6-12 Automatic Outages Initiated by Human Error

1.41% 6.57% 6.77% 6.87% 4.26% 6.55%

ALR6-13 Automatic Outages Initiated by Failed AC Substation Equipment

8.13% 5.59% 13.2% 8.14% 5.89% 6.19%

ALR6-14 Automatic Outages Initiated by Failed AC Circuit Equipment

2.83% 5.89% 5.08% 5.37% 4.58% 4.78%

ALR6-15 Element Availability Percentage

98.64% 98.41% 98.06% 97.86% 98.62% 97.89%

Comparison of ERCOT to NERC metrics for Adequate Level of Reliability measurements