Electricity Asset Management Plan 2019-2029
203
Vector Limited://
TARGETED OUTCOMES
CUSTOMER EXPERIENCE
SAFETY
RELIABILITY
RESILIENCE
OPERATIONAL EFFICIENCY
CYBER SECURITY AND PRIVACY
OPTIONS CONSIDERED FOR POLE MOUNTED AND GROUND MOUNTED TRANSFORMERS Options to address the need identified above have been assessed and are summarised in the following tables.
DESCRIPTION
DISCUSSION OF OPTION
ESTIMATED COST (NPV IF APPLICABLE)
STATUS
Option 1: Do nothing
There is a high risk that a bathtub curve scenario could eventuate where a sudden increase in deterioration / asset failures are likely and may encompass a greater number of assets that can be attended to under the budgeted corrective maintenance programme. This will have a negative impact on SAIDI and Asset Safety Incident rate service level. A ‘Do nothing’ approach is not recommended. The programme of works will see the replacement of ~ 1,556 pole mounted transformers that are forecast to have a health index of 7.5 at the end of the 10-year AMP period. This replacement number represents ~ 20% of the installed asset base. The program of works will also see the replacement of ~ 1,680 ground mounted transformers with a health index in excess of 7.5 within the 10-year AMP period, which represents ~ 10% of the installed asset base.
Rejected
Option 2: Undertake a staged and scheduled programme of works to replace pole mounted and ground mounted transformers prioritised by condition and criticality
$35.50M Selected
This programme of works will improve SAIDI and will reduce the H&S risk to the public and operational staff.
PROPOSED INVESTMENT SUMMARY ($MILLION NOMINAL)
DESCRIPTION
FY20
FY21
FY22
FY23
FY24
FY25
FY26
FY27
FY28
FY29 TOTAL
Auckland distribution transformer replacement Northern distribution transformer replacement
0.50
0.50
0.70
1.00
1.20
1.50
1.70
2.00
2.00
2.30
13.40
1.00
1.00
1.30
1.50
1.80
2.00
2.80
3.50
3.50
3.70
22.10
Total CAPEX
1.50
1.50
2.00
2.50
3.00
3.50
4.50
5.50
5.50
6.00
35.50
5.2.5 SECONDARY SYSTEMS AND OTHER NETWORK ASSETS The following sections set out the project proposals for Vector’s secondary systems and other network assets.
AUCKLAND AND NORTHERN DC SYSTEMS REPLACEMENT
NEEDS STATEMENT It is essential that zone substations have a secure DC supply because it is paramount for the safe and reliable operation of protection, control and interlocking. The need for a reliable DC supply becomes even more important during disturbances and faults in the distribution network or zone substation primary equipment. The 110 V DC system is continuously charged as a back-up power supply in the event of an AC outage on site and proper functioning of protection systems and reinstatement of electricity in zone substations post a fault are reliant on able and trustworthy 110 V DC systems.
An incident in 2016 during which a DC charger failure occurred at Keeling Road zone substation – during the incident the system failed to alert the SCADA master station and locked out the substation protection and control system. This
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