Electricity Asset Management Plan 2019-2029
117
Vector Limited://
The identification of serviceability or non-compliant asset observations consider generic performance and safety consequences. These consequences are used to determine the treatment criteria. The timeframes for treatment are strongly driven by the likelihood of the hazard. The applied maintenance approach has developed from a pure condition- based maintenance strategy to incorporate risk elements but the adoption of a more formal CBARM framework is in progress.
4.6.1 DISTRIBUTION GROUND MOUNTED SWITCHGEAR Overview
The function of HV distribution switchgear is to connect underground HV cable circuits together to form functional circuit rings that can be switched from two or more ends. Our distribution switchgear comprises varying ages and types of gear including oil-filled, SF6 and a small population of epoxy resin insulated equipment. One of the challenges facing Vector is an ageing 11 kV RMU population but we do not yet have evidence of systemic failures. However, we have experienced catastrophic and highly visible failures of oil filled switchgear in recent years. Some of the older brands and models of our ageing oil-filled ring main population also do not adhere to the latest Health and Safety codes of practice for the protection of operating personnel and the public against the risk of arc flash. Population and Age The table and graphs below describe the population and age of Vector’s 22 kV and 11 kV RMU population in distribution substations.
DESCRIPTION
AUCKLAND
NORTHERN
No of 11 kV distribution ground mounted oil filled switches
6121
1433
No of 11 kV distribution ground mounted switches with solid insulation
0
106
No of 11 kV distribution ground mounted SF 6
switches
883
594
No of 22 kV distribution ground mounted SF 6
switches
195
0
Table 4-19 Key statistics for Distribution Ground Mounted Switchgear
Figure 4-25 Age Profile for Distribution Ground Mounted Switchgear Auckland
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