Page of 8 ELECTRIC INFRASTRUCTURE RELIABILITY PERFORMANCE INDICATORS 7 8 9 0 FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE General THESL tracks reliability performance indicators System Average Interruption Frequency Index ( SAIFI ), System Average Interruption Duration Index ( SAIDI ), and Customer Average Interruption Duration Index ( CAIDI ) in three ways: ) Including all events; ) Without Major Event Days ( MEDs ); and ) Without MEDs and Loss of Supply. 7 8 MED is defined by standard P/D of the Institute of Electrical and Electronics Engineers ( IEEE ) as events that are beyond the design and/or operational limits of a utility. The removal of MEDs allows a utility to normalize its reliability data to make trending and goal setting possible. An example of a normalizing application was the OEB-allowed modification of 00 reliability data in light of the August, 00 provincial blackout. 9 0 7 8 Since 998, THESL has experienced the following MEDs: ) August -, 00 days, due to the blackout ) September 9, 00 8.0 minutes, due to Hurricane Isabel ) July, 00.9 minutes, due to the loss of supply to Esplanade TS ) August 9, 00 9. minutes due to major storm (thunderstorm) ) August 0, 00. minutes due to major storm (thunderstorm) ) July 7, 00. minutes, due to major storm (thunderstorm) 7) August, 00 7.0 minutes, due to loss of supply to Scarborough TS 8) March, 007. minutes due to a major ice storm
Page of 8 9) June 8, 007. minutes due to a major storm (thunderstorm) 0) January, 009.98 minutes due to Dufferin TS flooding ) April, 009.9 minutes due to major storm (thunderstorm) 7 8 9 0 Five-Year Historical Reliability Performance Tables, and along with Chart, and illustrate THESL s five-year historical reliability performance. With reference to Table, the SAIFI and SAIDI targets for 009 without MEDs are.87 interruptions per customer and. hours of interruptions per customer respectively based on system five-year average from 00 to 008. However, Table : Reliability Performance without MEDs and Loss of Supply most closely reflects the performance of the distribution system. Table : Reliability Performance (including all events) Service Reliability Indicators 00 00 00 007 008 Performance Measures (all events) Actual Actual Actual Actual Actual SAIFI (number of interruptions per customer).9.0.7.8.7 SAIDI (number of hours of interruption per customer).0.7.7.9. CAIDI (number of hours per interruption) 0.9 0.87 0.7 0.8 0.7
Toronto Hydro-Electric System Limited Page of 8
Page of 8 Table : Reliability Performance without MEDs Service Reliability Indicators Performance Measures (without MEDs) SAIFI (number of interruptions per customer) SAIDI (number of hours of interruption per customer) CAIDI (number of hours per interruption) 00 00 00 007 008 Actual Actual Actual Actual Actual.70.8.0.0.7.0.... 0.9 0.7 0.0 0.7 0.70
Page of 8 Table : Reliability Performance without MEDs and Loss of Supply Service Reliability Indicators 00 00 00 007 008 Performance Measures (without MEDs and Loss of Supply) Actual Actual Actual Actual Actual SAIFI (number of interruptions per customer).0..8.77. SAIDI (number of hours of interruption per customer).00.7.7.. CAIDI (number of hours per interruption) 0. 0.7 0. 0.7 0.7 The performance reliability indicator SAIFI has increased from 00 to 00 but has shown some improvements from 007 to 008. The performance reliability indicator
Page of 8 SAIDI has increased from 00 to 007 but has shown some improvements in 008. The performance reliability indicators are monitored closely to validate the results of various capital and maintenance programs. 7 To summarize, system reliability performance has improved somewhat between 007 and 008 indicating that THESL s recent investment programs are beginning to have a positive effect. 8 9 0 Cause Code Analysis THESL tracks causes of service interruptions by the ten Primary Cause Codes as specified in Table. of the Electricity Distribution Rate Handbook. Charts and show the number of customer interruptions ( CI ) and the number of hours of customer interruptions ( CHI ) reliability performance from 00 to 008, for the ten Primary Cause Codes. 7 8 9 0 In 008, Defective Equipment was consistently the main cause of service interruption (8 percent in CI and percent in CHI). The other top causes in 008 for CI were Unknown ( percent), Foreign Interference (0 percent), Tree Contacts (8 percent), Adverse Weather (7 percent) and Loss of Supply ( percent). In conclusion, equipment failure continues to be the dominant cause of system outages. As expected, equipment aging, conditions and operating at end of life support this trend.
Page 7 of 8
Page 8 of 8 7 8 9 0 Defective Equipment Analysis THESL tracks detailed causes of service interruptions by additional sub-classification of causes in order to stratify the reliability data and ascertain root cause trends. For example: Primary Cause Code for Defective Equipment is further categorized by the system types: Overhead Equipment, Underground Equipment and Station Equipment. Charts and 7 show the CI and CHI performance from 00 to 008 excluding MEDs by system type for the two highest causes: overhead and underground systems. The distribution equipment reliability contribution in 008 for CI is as follows: 8 percent for underground equipment and 9 percent for overhead equipment. The distribution equipment reliability contribution in 008 for CHI is percent for underground equipment and percent for overhead equipment. 7 When comparing the overhead and underground system components, Charts and 7 show that the underground system continues to fail more frequently and is more difficult to restore.
Page 9 of 8
Page 0 of 8 7 8 Overhead and Underground Equipment Reliability Analysis Charts 8 and 9 show the CI and CHI performance of the top four Overhead Equipment causes for 00-008 excluding MEDs. Overhead switch failures were high in 008 and show an upward trend. Insulators and lighting arrestors are still the largest contributors to overhead system failures. THESL will continue to monitor both types of equipment and analyze failure modes to improve performance.
Page of 8
Page of 8 7 8 9 0 Charts 0 and show the CI and CHI performance of the top four Underground Equipment causes for 00-008 excluding MEDs. Underground direct buried cable was the major cause of both CI and CHI in 008. There was a small improvement in underground direct buried cable performance in 008, which was attributed to THESL s direct-buried cable replacement program and the cable injection program to rejuvenate the cables. Underground cable remains a significant issue in system performance and requires immediate attention. Underground cable failures contribute two to three times higher CI and CHI than any other component failure. As a result, a cable replacement program has been established to improved performance of this distribution component. In summary, the top contributors to underground equipment CI and CHI performance in 008 were Underground Cables, Elbows, Terminators and Potheads, Underground
Page of 8 Switches and Underground Transformers. These are key capital investment areas identified for reliability improvement.
Page of 8 7 8 9 Unknown Cause Reliability Analysis Unknown Cause is defined as interruptions with no apparent cause or reason for the outage. Experience indicates that the majority of Unknown Cause interruptions are occasioned by tree or animal contacts. Charts and, shown previously, demonstrate that the Unknown Cause reliability contribution in 008 was percent for CI and percent for CHI. 0 Unknown Cause interruptions are generally of short duration although they produce a substantial number of customer interruptions. They often require greater effort in field trouble-shooting because of their temporary nature.
Page of 8 Tree Contact-Cause Reliability Analysis Charts and, shown previously, demonstrate that Tree Contact Cause interruptions increased from 00 to 00 and decreased in 007 and 008. In 008, Tree Contact Cause contributed to 8 percent of the total CI and 0 percent of the total CHI. 7 8 9 0 Starting in 008, Toronto Hydro adopted and implemented a Reliability-Based tree trimming program. It is a departure from the traditional fixed area and cycle approach. The new methodology takes into consideration reliability performance of each feeder from tree-related outages as well as cost of trimming each feeder. The analysis yields a trimming cycle for each feeder that will deliver the optimum reliability performance for the amount of resource spent. Going forward, THESL will monitor all tree-related outages and investigate their cause along with last trimmed information to update and further improve the program. Implementation of Tree Proof construction as a standard will also help to reduce treerelated outages. 7 8 9 0 7 8 Foreign Interference Cause Reliability Analysis THESL tracks detailed causes of Foreign Interference by internal sub-secondary Cause Codes. Charts and show the CI and CHI performance of the detailed causes of Foreign Interference for 00-008 excluding MEDs. The top causes for Foreign Interference are animal and vehicle. Animal Contact continues to have a large impact on system reliability performance and continues to be a challenge to address. Toronto s large tree canopy provides animals with access to the overhead system. In addition to the tree trimming program, the installation of animal guards on insulators and switches will help prevent animal contact. The Vehicle Interference trend is increasing and THESL utilizes options such as pole relocation and pole protection along with other design practices to deal with this rising trend.
Page of 8
Page 7 of 8 7 8 Conclusion The reliability performance indicators provide THESL with an overall measure of the performance of the electrical distribution system. Further analyses provide THESL information on which areas of the distribution system need attention. Capital and maintenance programs are set up to target the various systems and sub-systems for performance improvement. 9 0 The reliability performance indicators have increased from 00 to 007 and have shown some improvement in 008. The underground system, and in particular underground direct buried cable, continues to have a significant impact on system performance.
Page 8 of 8 Sustained capital and maintenance programs for high impact components affecting system reliability are required to maintain and improve system performance.