37
Toronto Hydro-Electric System Limited EB-2011-0144 Exhibit D1 Tab 7 Schedule 3 ORIGINAL Page 1 of 37 DISTRIBUTION SYSTEM – ELECTRIC INFRASTRUCTURE 1 RELIABILITY PERFORMANCE INDICATORS 2 3 FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE 4 THESL tracks System Average Interruption Frequency Index (“SAIFI”), System Average 5 Interruption Duration Index (“SAIDI”), and Customer Average Interruption Duration 6 Index (“CAIDI”) in the following ways: 7 Including all events 8 Excluding Major Event Days (“MEDs”) 9 Excluding MEDs and Loss of Supply 10 11 In addition to these performance indicators, THESL also provides a breakdown of 12 Scheduled Outages in each of the five years. Similar to Loss of Supply and MEDs, 13 Scheduled Outages affect the system adversely but do not represent the true state of 14 THESL’s distribution system. 15 16 FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE 17 The following Figures 1 and 2 demonstrate total number of Customers Interrupted (“CI”) 18 and total Customer Hours Interrupted (“CHI”) for the system over the past five years, 19 respectively. The four CI and CHI values for each year represent the effects of MEDs, 20 Loss of Supply and Scheduled Outages relative to all other type of system outages. 21

DISTRIBUTION SYSTEM – ELECTRIC … DISTRIBUTION SYSTEM – ELECTRIC INFRASTRUCTURE 2 RELIABILITY PERFORMANCE INDICATORS 3 4 FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE 5 THESL tracks

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Page 1: DISTRIBUTION SYSTEM – ELECTRIC … DISTRIBUTION SYSTEM – ELECTRIC INFRASTRUCTURE 2 RELIABILITY PERFORMANCE INDICATORS 3 4 FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE 5 THESL tracks

Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 1 of 37

DISTRIBUTION SYSTEM – ELECTRIC INFRASTRUCTURE 1

RELIABILITY PERFORMANCE INDICATORS 2

3

FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE 4

THESL tracks System Average Interruption Frequency Index (“SAIFI”), System Average 5

Interruption Duration Index (“SAIDI”), and Customer Average Interruption Duration 6

Index (“CAIDI”) in the following ways: 7

• Including all events 8

• Excluding Major Event Days (“MEDs”) 9

• Excluding MEDs and Loss of Supply 10

11

In addition to these performance indicators, THESL also provides a breakdown of 12

Scheduled Outages in each of the five years. Similar to Loss of Supply and MEDs, 13

Scheduled Outages affect the system adversely but do not represent the true state of 14

THESL’s distribution system. 15

16

FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE 17

The following Figures 1 and 2 demonstrate total number of Customers Interrupted (“CI”) 18

and total Customer Hours Interrupted (“CHI”) for the system over the past five years, 19

respectively. The four CI and CHI values for each year represent the effects of MEDs, 20

Loss of Supply and Scheduled Outages relative to all other type of system outages. 21

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 2 of 37

Figure 1: System Level CI 1

Figure 2: System Level CHI 2

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 3 of 37

MAJOR EVENT DAYS 1

An MED is defined by standard P1366/D12 of the Institute of Electrical and Electronics 2

Engineers (“IEEE”) as “events that are beyond the design and/or operational limits of a 3

utility”. The removal of MEDs allows a utility to normalize its reliability data to make 4

trending and goal setting possible. An example of a normalizing application was the 5

OEB-allowed modification of 2003 reliability data, in light of the August 14, 2003 6

provincial blackout. 7

8

MEDs experienced by THESL since 2003 are shown in Table 1 below: 9

10

Table 1: Major Event Days 11

Date Description Category SAIDI

August 14–15, 2003 Blackout Loss of Supply 2 days

September 19, 2003 Hurricane Isabel Adverse Weather 8.01 minutes

July 26, 2005 Loss of Supply to Esplanade TS Loss of Supply 6.93 minutes

August 19, 2005 Major Storm (Thunderstorm) Adverse Weather 19.16 minutes

August 20, 2005 Major Storm (Thunderstorm) Adverse Weather 6.44 minutes

July 17, 2006 Major Storm (Thunderstorm) Adverse Weather 12.46 minutes

August 21, 2006 Loss of Supply to Scarborough TS Loss of Supply 7.30 minutes

March 2, 2007 Major Ice Storm Adverse Weather 24.21 minutes

June 8, 2007 Major Storm (Thunderstorm) Adverse Weather 11.63 minutes

January 15, 2009 Dufferin TS Flooding Adverse

Environment 54.98 minutes

April 25, 2009 Major Storm (Thunderstorm) Adverse Weather 12.69 minutes

August 20, 2009 Major Storm (Thunderstorm) Adverse Weather 13.69 minutes

August 22, 2009 Major Storm (Thunderstorm) Adverse Weather 10.42 minutes

July 5, 2010 Loss of Supply to Manby TS Loss of Supply 21.61 minutes

Figure 3 demonstrates the contribution of the different categories of MEDs over the past 12

five years: 13

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 4 of 37

Figure 3: SAIDI Impact from MEDs 1

2

MEDs have played a large part in contributing to system CI and CHI in all years as 3

shown by the following Figures 4 and 5. The exception is 2008 in which THESL did not 4

experience any MEDs. As evident from the graph, adverse weather outages contribute 5

most to THESL MEDs; such outages are largely attributable to the overhead (“OH”) 6

system. THESL capital plan initiatives will help reduce the impact of weather related 7

outages by re-designing the OH system over the past five years. Although adverse 8

weather has the greatest contribution overall, the largest single event, as seen in the 9

adverse environment cause code, was a total station outage due to flooding at Dufferin 10

TS in 2009. 11

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 5 of 37

Figure 4: System CI due to Major Event Days, Loss of Supply and Planned Outages 1

2

3

LOSS OF SUPPLY 4

Loss of Supply (“LoS”) events continue to have a significant impact on the overall 5

reliability of the system. In 2010, a total of 21 LoS events affected the system while in 6

2009, 16 such events occurred. The top three events in terms of CI accounted for 43 7

percent of the total CI due to LoS in 2010. Similarly, the top three LoS events in terms of 8

CHI accounted for 70 percent of the total CHI due to LoS in 2010. These do not include 9

the MED on July 5, 2010. Figures 4 and 5 show the CI and CHI from the past five years 10

due to the LoS. On a system level, LoS can affect up to ten percent of the SAIDI and 11

SAIFI (excluding MEDs). While THESL does not have direct control over such events, 12

it can reduce the impact of LoS outages through initiatives such as stations ties or feeder 13

MED CI Loss of Supply CI Planned Outages CI

2006 76,898 145,193 34,413

2007 182,586 164,120 19,334

2008 0 70,382 18,355

2009 155,254 103,672 28,048

2010 123,455 161,907 51,501

Total 538,193 645,274 151,651

020,00040,00060,00080,000100,000120,000140,000160,000180,000200,000

Custom

ers Interrup

ted

System CI due to MED, LOS, and Planned Outages

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 6 of 37

automation. The overall performance of the THESL system is strongly impacted by 1

changes in LoS year-over-year, but THESL has no direct control over LoS. By excluding 2

this factor, THESL is able to monitor and asses the true state of its distribution system. 3

Figure 5: System CHI due to Major Event Days, Loss of Supply and Planned 4

Outages 5

6

7

SCHEDULED OUTAGES 8

Given the deteriorating asset condition of THESL’s system, more Scheduled Outages 9

have been required year-over-year since 2008. These outages improve the reliability of 10

the system in a planned manner. Figures 4 and 5 illustrate the impact of such outages on 11

CI and CHI, respectively. 12

MED CHI Loss of Supply CHI Planned Outages CHI

2006 222,814 46,647 36,938

2007 405,772 66,987 22,570

2008 0 18,851 25,353

2009 1,048,731 94,894 21,726

2010 255,340 76,718 111,653

Total 1,932,658 304,097 218,241

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

Custom

er Hou

rs In

terrup

ted

System CHI due to MED, LOS, and Planned Outages

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 7 of 37

1

From 2009 to 2010, THESL saw a significant increase in the number of scheduled 2

outages that is reflected proportionally in the CI and CHI for this cause code. In 2010, 3

Scheduled Outages contributed 4.2 percent to SAIFI and 12.4 percent to SAIDI. The 4

increase in the number of Scheduled Outages is required to replace ageing infrastructure. 5

Although this increased capital work has reduced the overall reliability of the system in 6

the short-term, the long-term improvements outweigh the short-term impact. 7

8

SYSTEM RELIABILITY EXCLUDING LOSS OF SUPPLY, MAJOR EVENT DAYS AND 9

SCHEDULED OUTAGES 10

THESL has very limited control over Major Event Days and Loss of Supply events. As a 11

result, the impact of these factors will be excluded from further analysis of the overall 12

system performance. In addition, because Scheduled Outages are required in order to 13

replace assets that are at end-of-life, THESL will also be excluding the reliability impact 14

of these planned outages from the analysis of the system performance. 15

16

Taking into account Adverse Environment, Adverse Weather, Defective Equipment, 17

Foreign Interference, Human Element, Lightning, Tree Contacts, Unknown and 18

excluding MEDs, LoS and Scheduled Outages, the true performance of assets that were 19

planned to remain in service for each year can be further analyzed. Figures 6, 7, and 8 20

show the SAIFI, SAIDI, and CAIDI performance indicators of the system, respectively, 21

excluding the following: MEDs, LoS events and Scheduled Outages. 22

23

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 8 of 37

Figure 6: System SAIFI Excluding MEDs, LoS and Scheduled Outages 1

Figure 7: System SAIDI Excluding MEDs, LoS and Scheduled Outages 2

2006 2007 2008 2009 2010

System SAIFI 1.79 1.74 1.63 1.45 1.46

0.000.200.400.600.801.001.201.401.601.802.00

System SAIFI

2006 2007 2008 2009 2010

System SAIDI 1.11 1.22 1.18 1.21 1.02

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

System SAIDI

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL Page 9 of 37

Figure 8: System CAIDI Excluding MEDs, LoS and Scheduled Outages 1

2

In 2010, system SAIFI remained at the same level as 2009, while system SAIDI saw 3

improvement. The SAIDI improvement is due to lower CHI from defective equipment 4

and foreign interference related outages. Since CAIDI is defined as the ratio of SAIFI to 5

SAIDI, the SAIDI improvement led to the system CAIDI improvement for the year 2010. 6

7

CAUSE CODE ANALYSIS 8

THESL tracks causes of service interruptions using the ten primary cause codes, as 9

specified in Table 15.2 of the Electricity Distribution Rate Handbook. Figures 9 and 10 10

show the reliability performance for CI and CHI from 2006 to 2010 for the ten primary 11

cause codes respectively. 12

13

2006 2007 2008 2009 2010

System CAIDI 0.62 0.70 0.72 0.84 0.70

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

CAIDI

System CAIDI

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 10 of 37

Figure 9: System CI Cause Code Breakdown (Excluding MEDs) 1

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 11 of 37

Figure 10: System CHI Cause Code Breakdown (Excluding MEDs) 1

Table 2: 2010 SAIFI and SAIDI Contributions by Cause Codes 2

Cause Code Contribution % to SAIFI Contribution % to SAIDI

Defective Equipment 39.7 37.9

*Loss of Supply 13.2 8.5

Adverse Weather 10.8 9.8

Unknown 9.7 2.6

Foreign Interference 8.2 6.1

Tree Contacts 8.1 14.9

*Scheduled Outage 4.2 12.4

Human Element 3.1 1.3

Lightning 1.7 1.9

Adverse Environment 1.4 4.6

*Excluded from further analysis in this document to reflect the true status of the system.

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 12 of 37

In 2010, Defective Equipment continued to be the main contributor to SAIFI and SAIDI, 1

at 39.7 percent and 37.9 percent respectively. Adverse Weather, which contributed to 2

10.8 percent of SAIFI and 9.8 percent of SAIDI in 2010, had a far greater impact on 3

system reliability in 2010 compared to 2009. Foreign Interference accounted for 8.2 4

percent of system SAIFI and 6.1 percent of system SAIDI, yet improved from 2009 5

levels. Tree Contacts resulted in 8.1 percent of system SAIFI and 14.98 percent of 6

system SAIDI. 7

8

When reviewing each cause code year over year, it can be seen that Defective Equipment 9

and Foreign Interference with addition of 2010 year are showing an improving trend 10

while Scheduled Outages, Human Element, Adverse Weather and Tree Contacts are 11

showing deterioration. In order to provide a better understand of reliability trend, 12

THESL has provided an in depth analysis of each of these cause codes. 13

14

DEFECTIVE EQUIPMENT ANALYSIS 15

The following graphs further categorize Defective Equipment CI and CHI contribution 16

by distinguishing between the following four different categories: 17

• Underground Equipment (“U/G Equipment”) 18

• Overhead Equipment (“O/H Equipment”) 19

• Station Equipment (“STN Equipment”) 20

• Other Equipment (“OTHER Equipment”) 21

22

Figure 11 and 12 show the CI and CHI breakdown for each category of Defective 23

Equipment excluding MEDs. 24

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 13 of 37

Figure 11: Defective Equipment Breakdown (CI) 1

Underground Equipment

Overhead Equipment

Station Equipment

Other Equipment

2006 293,808 190,468 16,902 66,495

2007 365,677 171,736 34,905 2,287

2008 331,518 232,167 12,633 6,681

2009 256,934 239,523 16,275 5,248

2010 197,314 273,173 9,774 8,305

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

Custom

ers Interrup

ted

Defective Equipment: CI Contribution

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 14 of 37

Figure 12: Defective Equipment Breakdown (CHI) 1

2

As can be seen in Figures 11 and 12, the largest contributors to Defective Equipment CI 3

and CHI in 2010 were Defective Overhead and Underground Equipment. In 2010, 4

Overhead Equipment failures counted for 56 percent of the CI due to defective 5

equipment, while counting for 44 percent of the CHI contribution. In comparison, in 6

2006, overhead equipment counted for 33 percent of the CI and 26 percent of the CHI 7

contribution. This shows that over the years, the overhead system has become a major 8

contributor to the decline of system reliability. 9

10

Defective Overhead Equipment 11

In 2010, Overhead Defective Equipment accounted for about 22 percent of system-wide 12

SAIFI and about 17 percent of system wide SAIDI. Defective Overhead Equipment has 13

Underground Equipment

Overhead Equipment

Station Equipment

Other Equipment

2006 260,865 102,189 10,707 22,125

2007 298,330 133,632 46,958 1,598

2008 293,849 134,758 10,367 1,047

2009 233,955 192,458 33,608 11,946

2010 182,550 150,597 5,685 2,116

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

Custom

ers Hou

rs In

terrup

ted

Defective Equipment: CHI Contribution

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 15 of 37

had a significant impact on overall system reliability and has been deteriorating over the 1

past five years. 2

3

In general, a significant trend upwards is seen in defective Overhead Equipment failures. 4

More specifically, overhead switches, insulators, and lighting arrestor failures have had 5

increasing contributions to system reliability. These causes account for 82 percent of the 6

CI and 71 percent CHI of the total Overhead Equipment failures in 2010. In addition to 7

these assets, Overhead Conductors are another major contributor to Equipment CI and 8

CHI. Transformers, while not a significant contributor to CI and CHI, have the highest 9

number of failures in the Overhead system with 63 percent of those due to CSP 10

transformers. The number of outages year-over-year is reflected in defective Overhead 11

Equipment CI and CHI. 12

13

The overhead portion is beginning to show a deteriorating trend over the past three years. 14

From a SAIDI perspective, overhead outages account for 33 percent, 48 percent and 46 15

percent of the Defective Equipment-related outages from 2008 to 2010, and 42 percent, 16

49 percent and 58 percent of the Defective Equipment-related outages in SAIFI from 17

2008 to 2010, respectively. To further analyze the causes for the increase in CI and CHI 18

of the overhead system, major contributors for CI and CHI across the system are further 19

broken down by individual components. Figures 13, 14, and 15 portray the individual 20

overhead system components contribution to CI and CHI, as well as number of outages 21

due to overhead equipment failure. As evidenced by these figures, the major contributors 22

to overhead equipment failure have been deteriorating in the past five years. 23

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 16 of 37

Figure 13: Overhead Defective Equipment Major Contributors (CI) 1

Figure 14: Overhead Defective Equipment Major Contributors (CHI) 2

Switch Insulator ConductorLightning Arrestor

Transformers

2006 65,881  28,008  39,894  25,127  13,517 

2007 50,056  48,236  36,649  27,317  4,606 

2008 112,373  30,252  34,067  42,344  5,511 

2009 56,425  82,714  53,250  25,501  11,273 

2010 78,661  104,160  39,168  35,838  9,785 

20,000 

40,000 

60,000 

80,000 

100,000 

120,000 

Custom

ers Interrup

ted

Defective OH Equipment: CI Contribution

Switch Insulator ConductorLightning Arrestor

Transformers

2006 24,866 11,683 22,966 11,032 11,432

2007 19,714 52,322 38,865 10,764 7,412

2008 47,565 24,341 26,995 22,105 6,714

2009 29,844 71,766 42,367 33,628 6,057

2010 37,532 45,551 32,281 23,083 10,572

010,00020,00030,00040,00050,00060,00070,00080,000

Custom

er Hou

rs In

terrup

ted

Defective OH Equipment: CHI Contribution

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 17 of 37

Figure 15: Overhead Defective Equipment Major Contributors (Outages) 1

Switch Insulator ConductorLightning Arrestor

Transformers

2006 76 26 71 34 89

2007 66 36 70 43 83

2008 92 36 75 46 72

2009 53 62 71 41 65

2010 62 38 83 36 95

0102030405060708090

100

Num

ber o

f Outages

Defective OH Equipment: Number of Outages

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 18 of 37

Figure 16: CI Impact per Outage from Overhead Equipment 1

Figure 17: CHI Impact per Outage from Overhead Equipment 2

Switch Insulator ConductorLightning Arrestor

Transformers

2006 867  1,077  562  739  152 

2007 758  1,340  524  635  55 

2008 1,221  840  454  921  77 

2009 1,065  1,334  750  622  173 

2010 1,269  2,741  472  996  103 

0

500

1,000

1,500

2,000

2,500

3,000

Custom

ers Interrup

ted

Defective OH Equipment: CI Per Outage

Switch Insulator ConductorLightning Arrestor

Transformers

2006 327  449  323  324  128 

2007 299  1,453  555  250  89 

2008 517  676  360  481  93 

2009 563  1,158  597  820  93 

2010 605  1,199  389  641  111 

0200400600800

1,0001,2001,4001,600

Custom

er Hou

rs In

terrup

ted

Defective OH Equipment: CHI per Outage

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 19 of 37

Insulators 1

The five-year trend for insulators shows a large increase in CI and CHI. Insulators 2

account for 30 percent of the overhead system CHI and 40 percent of the overhead system 3

CI in 2010. Porcelain-type insulators account for approximately 70 percent of the 4

insulator CI and CHI. Although CI and CHI are on the rise, when looking at the number 5

of interruptions, it can be seen that the overall failures in the distribution system has 6

shown a slight improvement from 2009, but a deteriorating trend from 2006. This is due 7

to the proactive insulator replacement in projects. As evidenced by the figures above, 8

while insulator failures are lower in frequency compared to other major overhead assets, 9

such failures have the greatest impact on system reliability. In 2010, an insulator failure 10

on average led to 2741 customers interrupted. THESL intends to continue phasing out 11

the porcelain insulators across the system and replacing them with the more reliable 12

polymeric type insulators. 13

14

Conductors 15

Overhead conductor failures have been trending upwards over the past five years as 16

THESL’s overhead assets age. Overhead conductors are addressed as part of overhead 17

rebuild projects. 18

19

Lightning Arrestors 20

Lightning Arrestors cause about 15 percent of the Overhead Defective Equipment CI and 21

CHI. The system has experienced a decrease in number of outages from this asset class 22

over the past two years as the oldest and highest failure risk Lighting Arrestors have been 23

replaced. However, the five-year CI and CHI trends have been increasing. 24

25

Overhead Switches 26

From the CI and CHI figures, it can be seen that the CI and CHI closely mirror the 27

number of outages year-over-year. As shown in Figures 16 and 17, the CI and CHI per 28

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 20 of 37

Switch failure have steadily increased to 1,269 customers per outage with a total duration 1

of 605 hours per outage. THESL currently plans on addressing the impact of switch 2

failures and restoration time by increasing the number of switches and automated 3

switches in the system. This approach allows the affected locations to be isolated from 4

the system and the rest of the feeder to be restored. As more automated switches are 5

installed, the CI and CHI will improve. 6

7

Defective Underground Equipment 8

Even though Defective Underground Equipment has shown marked improvement in both 9

CI and CHI contribution over the last five years, it remains a significant contributor to 10

overall system SAIFI and SAIDI. In 2010, Defective Underground Equipment accounted 11

for about 16 percent of system wide SAIFI and about 20 percent of system wide SAIDI. 12

13

Figures 18 and 19 portray the CI and CHI contributions due to underground equipment 14

failure. 15

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 21 of 37

Figure 18: Underground Defective Equipment Major Contributors (CI) 1

Primary Cable & Joints

Submersible Transformer

Elbow Terminator SwitchgearAll other types

2006 153,297  19,571  13,896  13,259  59,403  34,382 

2007 250,498  28,048  22,417  17,777  24,283  22,654 

2008 220,246  21,263  11,604  7,408  35,989  35,008 

2009 180,708  13,133  26,412  5,096  23,560  8,025 

2010 147,105  13,799  1,887  3,622  20,407  10,494 

020,00040,00060,00080,000100,000120,000140,000160,000180,000200,000220,000240,000260,000

Custom

ers Interrup

ted

Defective U/G Equipment: CI Contribution

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 22 of 37

Figure 19: Underground Defective Equipment Major Contributors (CHI) 1

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 23 of 37

Figure 20: Underground Defective Equipment Major Contributors (Outages) 1

Primary Cable & Joints

Submersible Transformer

Elbow Terminator SwitchgearAll Other Types

2006 216 77 32 7 33 61

2007 245 66 38 16 16 71

2008 230 73 16 18 35 79

2009 223 59 31 8 26 47

2010 223 68 13 12 25 51

0

50

100

150

200

250

300

Num

ber o

f Outages

Defective UG Equipment: Number of Outages

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 24 of 37

Figure 21: CI Impact per Outage from Underground Equipment 1

Primary Cable & Joints

Submersible Transformer

Elbow Terminator SwitchgearAll Other Types

2006 710 254 434 1,894 1,800 564

2007 1,022 425 590 1,111 1,518 319

2008 958 291 725 412 1,028 443

2009 810 223 852 637 906 171

2010 660 203 145 302 816 206

0200400600800

1,0001,2001,4001,6001,8002,000

Custom

ers Interrup

ted

Defective UG Equipment: CI per Outage

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 25 of 37

Figure 22: CHI impact per Outage from Underground Equipment 1

2

3

Primary Cable 4

As can be seen in Figures 18 and 19, defective primary cable remains the largest 5

contributing factor to CI and CHI for defective underground equipment. This has a 6

significant overall impact on system reliability. In 2010, defective primary cable 7

contributed 12 percent to overall system SAIFI and 15 percent to overall system SAIDI, 8

and 75 percent to the Underground Defective Equipment category SAIFI and SAIDI. As 9

is evident in Figures 21 and 22, the average number of customers interrupted per failure 10

is 750 with an average total time of 750 hours. A significant portion of the primary cable 11

faults occur on direct-buried cable, a legacy standard, most of which is beyond the end of 12

its useful life. Capital investments in this asset class have been initiated to replace direct-13

buried primary cable with current standard cable in concrete encased duct. This 14

Primary Cable & Joints

Submersible Transformer

Elbow Terminator SwitchgearAll Other Types

2006 792 301 398 411 743 433

2007 832 328 593 686 967 335

2008 745 400 749 353 1,011 502

2009 770 342 423 545 661 159

2010 614 272 257 238 487 172

0

200

400

600

800

1,000

1,200

Custom

ers Hou

rs In

terrup

ted

Defective UG Equipment: CHI per Outage

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 26 of 37

investment has had favorable impacts on the overall system reliability, and as a result, 1

THESL plans to continue investing in the direct-buried primary cable removal project. 2

Both CI and CHI attributable to primary cable have declined since the introduction of this 3

project in 2007. From 2007 to 2010, a total reduction of 41 percent to the CI and 33 4

percent o the CHI has been realized. 5

6

Submersible Transformers and Elbows 7

In 2010 the second largest contributor to Defective Underground Equipment was 8

submersible transformers accounting for seven percent of Defective Underground 9

Equipment CI and ten percent of Defective Underground Equipment CHI. Due to capital 10

investment in this asset class over the last number of years, the general performance trend 11

is slightly improving. When legacy submersible transformers are replaced with standard 12

switchable ones, the elbows are also replaced because they are at the end of their useful 13

lives. The significant number of submersible transformers replaced over the last few 14

years has had a very favorable impact on the SAIFI and SAIDI contribution of elbows. 15

This trend can be seen in Figures 18 and 19 as elbow-related outages have decreased. 16

17

Switchgear 18

As can be seen from Figures 18 and 19, switchgear is also a significant contributor to 19

Defective Underground Equipment. The general trend of CI and CHI contribution from 20

defective switchgear over the last five years has slightly improved. In the past two years, 21

THESL has observed a decrease in the CI and CHI impact to the system from switchgear. 22

As evident from Figures 21 and 22, 816 customers are interrupted with each failure on 23

average with a total duration of 487 hours. Part of this reliability improvement can be 24

attributed to increased maintenance spending on the inspection and cleaning of pad-25

mounted switchgear. Capital expenditures are proposed in the ten-year plan to phase out 26

air insulated pad-mounted switchgear and replace it with sealed-type switch gear. One 27

such example of a sealed-type switchgear is the SF6 pad-mounted switchgear. The 28

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 27 of 37

switch contains SF6 gas inside of the sealed switchgear housing. This eliminates the 1

contamination from environmental factors that results in the failure of air-insulated 2

switchgear. 3

4

Human Element 5

Though Human Element has the smallest impact of all the cause codes, the CHI has been 6

showing an upward trend over the past five years and with the exception of 2009, the CI 7

has also been showing a similar trend. Human Element is caused when work by THESL 8

or THESL contractors creates an outage. From 2009 to 2010, the significant increase to 9

Scheduled Outages closely mirrors the increase in Human Element events. Like 10

Scheduled Outages, Human Element is directly impacted by the capital program and is 11

closely monitored by THESL as it involves employee safety. 12

13

Figure 23: Human Element Contribution (CI) 14

2006 2007 2008 2009 2010

CI 25,528 26,786 23,690 12,002 38,184

0

10,000

20,000

30,000

40,000

50,000

Custom

ers Interrup

ted

Human Element CI

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 28 of 37

Figure 24: Human Element Contribution (CHI) 1

2

3

Adverse Weather 4

In 2010, Adverse Weather contributed towards 10.8 percent of the system SAIFI and 9.8 5

percent of the system SAIDI. The number of outages due to Adverse Weather has been 6

trending down over the past five years, but the impact from Adverse Weather over these 7

years has increased. Figures 25, 26 and 27 show the trend of Adverse Weather outages 8

over the past five years. 9

2006 2007 2008 2009 2010

CHI 9,404 4,688 4,894 6,119 11,359

0

2,000

4,000

6,000

8,000

10,000

12,000

Custom

ers Hou

rs In

terrup

ted

Human Element CHI

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 29 of 37

Figure 25: Adverse Weather Contribution (CHI) 1

Figure 26: Adverse Weather Contribution (CHI) 2

2006 2007 2008 2009 2010

Adverse Weather 71,855 93,051 87,054 47,355 132,756

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

Custom

ers Interrup

ted

ADVERSE WEATHER CI

2006 2007 2008 2009 2010

Adverse Weather 52,659 78,367 74,520 65,084 88,001

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

Custom

er Hou

rs In

terrup

ted

Adverse Weather CHI

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 30 of 37

Figure 27: Adverse Weather Contribution (Outages) 1

2

CI due to adverse weather outages has shown an inconsistent yet upward trend over the 3

past five years. Storm hardening and conversion of overhead plant to underground will 4

reduce the vulnerability of the overhead system to adverse weather conditions. CHI due 5

to adverse weather has also been trending up over the last five years. Introduction of 6

Fault Current Indicators (“FCIs”) into the system will help localize faults and reduce 7

outage restoration times. 8

9

Foreign Interference 10

Foreign Interference continues to be a significant contributor to system reliability as 11

shown in Figures 28 and 29. A downward trend of foreign interference CI and CHI 12

contributing 8.2 percent to system SAIFI and 6.1 percent to system SAIDI, was shown in 13

2010. In the Foreign Interference category, THESL has some measure of control over 14

animal contact, where the installation of animal guards has led to a reduction in outages. 15

2006 2007 2008 2009 2010

Adverse Weather 129 130 111 88 79

0

50

100

150

Number of Adverse Weather Outages

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 31 of 37

Figure 28: Foreign Interference Breakdown (CI) 1

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 32 of 37

Figure 29: Foreign Interference Breakdown (CHI) 1

2

3

Tree Contacts 4

In 2010, Tree Contacts had a contribution of 8.1 percent to SAIFI and 14.9 percent to 5

SAIDI. Tree Contacts can be occur in adverse or normal weather conditions or through 6

brush contact. Figures 30, 31, and 32 provide a breakdown of the three types of Tree 7

Contact outages. 8

9

From Figure 9, it can be seen that CI due to Tree Contact has remained relatively stable 10

over the past years while Figure 10 shows the CHI increasing from 2009 to 2010. 11

Figures 30 and 31 further breaks down the Tree Contact cause code into “Adverse 12

Weather”, “Normal Weather” and “Brush Contact”. There is a significant increase in the 13

Adverse Weather CI and CHI when compared to 2009. When comparing Figures 33 and 14

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 33 of 37

34, it can be seen that the average number of customers interrupted has remained around 1

1,000 customers per Adverse Weather interruption over the past five years while the 2

duration has increased to 1,550 hours. When compared to Defective Equipment CI and 3

CHI per outage, Adverse Weather Tree Contacts would rank as one of the top categories. 4

Figure 30: Tree Contact Breakdown (CI) 5

Adverse Weather Normal Weather Brush Contacts

2006 106,449 33,917 16,939

2007 49,585 49,461 3,492

2008 61,536 24,518 8,774

2009 52,282 36,758 5,689

2010 71,516 22,617 4,822

0

20,000

40,000

60,000

80,000

100,000

120,000

Custom

ers Interrup

ted

Tree Contacts: CI Breakdown

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 34 of 37

Figure 31: Tree Contact Breakdown (CHI) 1

Figure 32: Tree Contact Breakdown (Outages) 2

Adverse Weather Normal Weather Brush Contacts

2006 101,353 21,333 4,404

2007 27,905 35,692 2,163

2008 71,650 12,184 1,639

2009 53,448 22,694 3,692

2010 103,871 19,347 10,316

0

20,000

40,000

60,000

80,000

100,000

120,000

Custom

ers Hou

rs In

terrup

ted

Tree Contacts: CHI Breakdown

Adverse Weather Normal Weather Brush Contacts

2006 105 46 15

2007 45 66 5

2008 71 32 11

2009 51 35 5

2010 67 40 12

0

20

40

60

80

100

120

Num

ber o

f Outages

Tree Contacts: Number of Outages

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 35 of 37

Figure 33: CI per Tree Contact Event 1

2

Adverse Weather interruptions are caused by severe storms or high wind conditions. 3

During these times, tree branches can break off and fall onto THESL conductors. From 4

2006 to 2010, THESL has observed 50, 26, 42, 29 and 24 unique days respectively in 5

which Adverse Weather Tree Contacts occurred. A unique Adverse Weather day is any 6

one day in which one or more Adverse Weather Tree Contact takes place. Taking the 7

total number of Adverse Weather Tree Contact interruptions and dividing it by the total 8

number of unique days, will result in the number of Tree Contact outages per Adverse 9

Weather day. This is represented in Figure 35 below. 10

Adverse Weather Normal Weather Brush Contacts

2006 1,014 737 1,129

2007 1,102 749 698

2008 867 766 798

2009 1,025 1,050 1,138

2010 1,067 565 402

0

200

400

600

800

1,000

1,200

Custom

ers Interrup

ted

Tree Contacts: CI Per Event

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 36 of 37

Figure 34: CHI per Tree Contact Event 1

Adverse Weather Normal Weather Brush Contacts

2006 965 464 294

2007 620 541 433

2008 1,009 381 149

2009 1,048 648 738

2010 1,550 484 860

0200400600800

1,0001,2001,4001,6001,800

Custom

ers Hou

rs In

terrup

ted

Tree Contacts: CHI Per Event

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Toronto Hydro-Electric System Limited EB-2011-0144

Exhibit D1 Tab 7

Schedule 3 ORIGINAL

Page 37 of 37

Figure 35: Outages per Adverse Weather Day 1

2

From Figure 35, it can be seen that even though in 2010 THESL had less storm days than 3

any of the previous years, when comparing the Average Outages per Adverse Weather 4

day, there is a significant increase. Though there were fewer days in which Adverse 5

Weather Tree Contacts occurred in 2010, the storms were more severe and caused more 6

damage to the system. 7

8

CHI is an indication of how quickly THESL can respond to outages across the system. It 9

can be seen from Figure 31 that the CHI due to Adverse Weather increased significantly 10

in 2010. This is due to the concentration of the events occurring simultaneously and 11

adversely affecting THESL response time. 12

2006 2007 2008 2009 2010

Outages per Adverse Weather Day 2.10 1.73 1.69 1.76 2.79

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Outages

Outages per Adverse Weather Day