Electricity Asset Management Plan 2019-2029
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Vector Limited://
ROUTINE AND CORRECTIVE MAINTENANCE AND INSPECTIONS
FY19 – FY28
Distribution feeders
61%
Distribution substations and transformers
13%
Secondary systems
5%
Subtransmission feeders
6%
Zone substations
15%
Table 5-2 Routine and corrective maintenance and inspections expenditure allocation
NETWORK MAINTENANCE NEEDS STATEMENT Achieving the corporate objectives will require the balancing of cost, risk and performance outcomes to gain optimal value from assets without compromise to service levels, reliability indices and the experience of customers. To achieve the required network performance efficiently the condition of individual assets must be maintained in a serviceable operating state over the period of its useful life. To deliver on this Vector implements extensive routine and operational preventative activities. Equipment is inspected at scheduled intervals for physical indications of degradation exceeding a threshold that is predictive of a potential failure. Typical examples of inspection and condition monitoring activities include: analysis of power transformer oil to monitor for trace gasses produced by internal faults; inspection of service lines; acoustic inspections to identify partial discharge; assessing the extent of decay in timber power poles to determine residual strength and; inspection of timber cross-arms to detect visible signs of degradation. Pole and/or crossarm replacement occurs through a combination of failed inspections and proactive replacement where age, type, location, risk and criticality are considered. Proactive pole and crossarm replacement is also undertaken in conjunction with reconductoring projects. However, analysis of our service levels and reliability indices show that a number of performance issues are developing within our asset base that requires Vector to take a different approach and/or additional programmes of maintenance to prevent service level gaps from deteriorating any further. Our performance gap analysis and root cause analysis shows that: • The failure of components of overhead lines contribute significantly to interruptions on distribution feeders • There could be a potentially increasing trend of failure of underground 11 kV cables and joints that contribute to interruptions on distribution feeders • Third party damage to our assets is contributing significantly to poor service level outcomes. • Pole mounted 11 kV cast iron pothead cable boxes were found to be a primary contributor to interruptions on distribution feeders • Vegetation in the proximity of our overhead power lines is a major factor in network outages especially during storms and high winds (additional maintenance spend will be directed at Vegetation – see separate Needs Statement further below) In general, there is an increasing number of open, high risk corrective notifications in our inspections database and the number of unplanned events are rising and needs to be addressed (refer to Section 4.1.7). To reduce our open, high risk corrective notifications and improve our service levels we will undertake the following as part of our corrective maintenance investment: • Fully implement the proposed changes to SAP-PM to support the new maintenance standards. This will enable the collection of better condition data and the improved management of planned and corrective work. • Increase focus and investment to remediate open, high risk corrective notifications • Traditionally conductor clearance to ground issues have been identified primarily as part of planned inspections of poles structures. This method is too time consuming and does not address in a timely manner the legislative risks with regard to low conductors. We will increase our use of light detection and ranging (LiDAR) to speed up the survey of OH line clearances • Increase the level and skill set of reactive response field staff • Increase the use of diagnostic measurement techniques such as ultrasonic partial discharge surveys on our network. • Increase and improve our diagnostic testing on our subtransmission and 11 kV distribution cable fleet • Increase partial discharge and acoustic surveys on switchgear Our maintenance regime and frequencies of inspection for planned maintenance are described in our suite of maintenance standards for our different asset classes. Each maintenance standard addresses the purpose, content, frequency, record requirements and associated treatment criteria. The treatment criteria and resulting actions generally
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