Asset Management Plan – High Voltage Circuit Breakers

1 Approved By: Prepared By: Issue Date: 22/02/2018 Next Review: 31/12/2019 Status: Approved Executive General Manager Power Networks Group Manager Asset Strategy Document No.: D2017/242384 Version No: THIS STANDARD IS UNCONTROLLED WHEN PRINTED PAGE 1 OF 58 Asset Management Plan high Voltage Circuit Breakers Power and Water Corporation CONTROLLED DOCUMENT Executive Summary .. 3 1 Purpose .. 5 2 Scope .. 6 Asset class overview .. 6 Asset class function .. 6 Asset objectives .. 7 3 Context .. 9 Roles and responsibilities .. 9 RACI .. 9 Identification of needs .. 11 Selection of options and solutions .. 11 4 Asset base .. 12 Overview .. 12 Asset types .. 12 Breakdown of Asset population .. 12 Type issues .. 15 Asset profiles .. 19 5 Health and criticality profiles .. 21 Asset 22 Criticality .. 25 Network risk .. 26 Environmental challenges .. 26 Operational challenges .. 27 Asset challenges.

2 29 6 Performance indicators .. 30 7 Growth requirements .. 30 Establish a new Wishart zone substation .. 31 Attachment Class Management Plan high Voltage Circuit Breakers PAGE 2 OF 58 THIS DOCUMENT IS UNCONTROLLED WHEN PRINTED Archer 3rd Transformer .. 32 Long term growth .. 32 8 Renewal and maintenance requirements .. 32 Projects currently in progress .. 33 66 kV ASEA HLC Circuit Breakers .. 34 Berrimah .. 35 Humpty Doo .. 36 Centre Yard .. 37 Random Asset failure .. 37 Long-term (8-12 years) renewal needs .. 39 9 Investment program .. 40 Augmentation expenditure (augex) .. 40 Renewal expenditure (repex) .. 41 Operational expenditure (opex) .. 43 10 Asset class outcomes .. 44 Network risk .. 44 11 Performance monitoring and improvement .. 45 Monitoring and improvement .. 45 12 Appendix A Lifecycle Asset Management .. 46 Planning (augmentation) .. 46 Design .. 47 Operation.

3 48 Maintenance (opex) .. 48 Renewal (repex) .. 49 Disposal .. 49 13 Appendix B Asset data .. 50 CB volumes by location and Voltage .. 50 Age profiles .. 51 Asset Class Management Plan high Voltage Circuit Breakers PAGE 3 OF 58 THIS DOCUMENT IS UNCONTROLLED WHEN PRINTED Executive Summary Power and Water Corporation (Power and Water) owns and operates the electricity transmission and distribution networks in the Northern Territory of Australia. Included in the networks are high Voltage (HV) Circuit Breakers which perform a critical function in maintaining the business objectives of delivering a safe and reliable supply of electricity to Power and Water s customers. Assets contribute a sizeable proportion to the total Asset base only a relatively small number of Circuit Breakers are close to the end of their expected serviceable lives HV Circuit Breakers make up 6% of the total network value of the Asset base.

4 It is a fairly young Asset fleet, but varies by Voltage level. The 132 kV Circuit Breakers have the oldest average age as the lower Voltage levels have been subject to renewal programs during the past few years. There are approximately 37 Circuit Breakers that currently exceed their expected serviceable life and are generally in poor condition, but there are projects in place to address this risk. Assets operate across a diverse environment temperature, humidity, rainfall, termites, soil types present a challenge to managing the assets. The Power and Water power network is subject to unique environmental and operational challenges ranging from the coastal tropical environments prone to cyclones, high temperatures and humidity, and high annual rainfall, to desert environments subject to high ambient temperatures, occasional flooding, and surrounding factors including high termite infestation and aggressive soil conditions.

5 This unique environment results in a more rapid rate of Asset deterioration, and lower worker productivity compared to peer distribution businesses. The key impact by these climatic conditions is high moisture content in insulation oil, particularly for free breathing type Circuit Breakers . This has resulted in the deterioration of a specific type of Circuit breaker and emergence of a type issue. Asset Management challenges emerging type issues and data integrity. In general, the Asset fleet is young and the projects planned to be implemented by the end of FY24 will remove a significant portion of the existing network risk. However, there are some emerging issues that need to be monitored to avoid major failures and outages. The key issues are SF6 gas leakage, amounting to approximately 130 kg per year and three Circuit Breakers that are unable to be effectively maintained in situ or removed from service.

6 They are currently assessed as critical (C3) but in good condition (H1). Focused routine inspections and targeted inspections and testing prioritising high risk areas are some of the proposed undertakings aimed at improving efficiency and improving data collection and analysis during business as usual activities. Improved data will enable more advanced analysis and modelling to be undertaken to better support Asset Management decision making Investment programs are targeted to manage the key challenges directed replacement. In addition to a number of project that are currently under way and that will be completed during the current regulatory period, there are a number of augmentation and Asset renewal programs are proposed for the 2019/20 to 2023/24 regulatory period: Asset Class Management Plan high Voltage Circuit Breakers PAGE 4 OF 58 THIS DOCUMENT IS UNCONTROLLED WHEN PRINTED Establishing a new Wishart ZSS Replacement of the HLC Circuit Breakers due to a type issue Renewing Berrimah, Humpty Doo and Centreyard ZSS to address condition and safety concerns The augmentation and renewal projects have been developed with the objective of managing the network risk.

7 This risk would grow overtime as the demand increases and Circuit breaker condition deteriorates. The projects selected for the next regulatory period will mitigate the excessive network risk and return it to a level that is sustainable in the long term. The power transformer programs are summarised as follows: Investment category 2019-20 ($ million) 2020-21 ($ million) 2021-22 ($ million) 2022-23 ($ million) 2023-24 ($ million) Total ($ million) Augmentation $ $ $ $ $ $ Renewal $ $ $ $ $ $ Maintenance Plans $ $ $ $ $ $ Total $ $ $ $ $ $ Benefits from the investment program network risk The investments are not expected to impact the system performance directly, however, they will reduce the total risk on the network and reduce the operational expenditure required at these substations. The reduction of risk on the network is shown through the Asset health assessment and criticality assessment.

8 Table shows the current network risk. Table shows the network risk at the end of the next regulatory period once the above mentioned projects have been completed. The tables demonstrate there will be a reduction in network risk, bringing it to a sustainable level that is suitable for Power and Water. Table Current Circuit breaker risk matrix H1 H2 H3 C1 435 36 49 C2 6 0 6 C3 35 0 3 Table Circuit breaker risk matrix with investment H1 H2 H3 C1 479 33 25 C2 9 0 3 C3 37 0 1 Asset Class Management Plan high Voltage Circuit Breakers PAGE 5 OF 58 THIS DOCUMENT IS UNCONTROLLED WHEN PRINTED 1 Purpose The purpose of this Asset Management plan (AMP) is to define Power and Water Corporation s (Power and Water) approach to managing its high Voltage Circuit Breakers located in zone substations. It frames the rationale and direction that underpins the Management of these assets into the future: Short Term (0-2 years): Detailed maintenance and capital works plans for the upcoming financial year based on current Asset condition.

9 Medium Term (3-7 years) 2019-24 Regulatory Control Period: Strategies and plans based on trends in performance and health indicators. Long Term (8-12 years) 2024-29 Regulatory Control Period: Qualitative articulation of the expected long-term outcomes. The HV Circuit breaker assets are managed to comply with the broad external requirements of legislation, codes and standards. This is achieved within an internal framework of policy, strategy and plans that are enabled through interrelated documents, systems and processes that establish the Power Networks Asset Management practices. The Asset Management system is summarised in Figure 1-1. Figure 1-1 Asset Management System Asset Class Management Plan high Voltage Circuit Breakers PAGE 6 OF 58 THIS DOCUMENT IS UNCONTROLLED WHEN PRINTED 2 Scope Asset class overview In-scope assets include all HV Circuit breaker located within securely fenced zone substations with nominal primary voltages between 11 kV and 132 kV.

10 The Asset group excludes power transformers and other HV assets located within the zone substation boundaries. This AMP also does not include instrument transformers, auxiliary transformers, surge arresters, protection equipment ( HV fuses, relays, etc.), DC systems, SCADA, DSA and Load Control (Frequency Injection) equipment, buildings, fences and other civil infrastructure within zone substations. Table : Overview of in-scope assets at 30 June 2017 Voltage kV Quantity Economic lifespan (years) Average age (years) Number exceeding economic lifespan in forecast period Average remaining life of assets not exceeding economic lifespan (years) Qty % 11 kV 300 45 20 22 kV 126 45 13 66 kV 104 45 3 132 kV 40 45 - Totals 570 45 36 Further information on Power and Water s high Voltage Circuit Breakers assets, such as quantities, locations, manufacturers, types, etc.