Electricity Asset Management Plan 2019-2029
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Vector Limited://
roadmap. Trials are on-going at the time of writing, of equipment that will improve the visibility and controllability of distribution transformers.
The strategy also includes all new installations with transformers larger than 500 kVA having appropriate and fast acting arc flash protection in place on the high current, i.e. LV side.
4.6.3 DISTRIBUTION SUBSTATIONS LV FRAMES Vector has a sizeable population of old style DIN-type vertical fuse disconnect LV frames. This style of LV frame holds a higher risk of arc-flash to operators when a fuse is pulled under energised conditions. Vector will undertake a risk-based assessment for a programme to upgrade to modern LV frames that for larger transformers (larger than 500 kVA) will include a CB to further reduce the risk and consequences of arc-flash. At the time of writing, this strategy is to be developed. Risks are covered by operational instructions.
4.6.4 DISTRIBUTION POLE MOUNTED TRANSFORMERS Overview
Our population of pole mounted transformers are either 11 kV / 415 V three-phase or 11 kV / 230 V single phase transformers and they are the mainstay in our rural networks - we have no 22 kV pole mounted transformers. Pole mounted transformers are installed on either single or double poles depending on its kVA rating but because of seismic risks, pole mounted transformers larger than 300 kVA are not installed on poles.
Population and Age The table and graphs below provide details of our pole mounted transformer population and age.
DESCRIPTION
AUCKLAND
NORTHERN
No of distribution pole mounted transformers 11 kV, 5 kVA to 30 kVA No of distribution pole mounted transformers 11 kV, > 30 kVA to 100 kVA No of distribution pole mounted transformers 11 kV, > 100 kVA to 300 kVA
431
4148
369
1451
988
23
Table 4-21 Key statistics for Distribution Pole Mounted Transformers
Figure 4-34 Age Profile for Distribution Pole Mount Transformers – Auckland
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