Electricity Asset Management Plan 2019-2029
92
Vector Limited://
Population and age The figure below summarises the age of our 110 kV subtransmission cable fleet.
Figure 4-6 Age profile for 110 kV subtransmission cables
Condition and health The oldest 110 kV cables in Vector’s fleet are the two cables from Mt Roskill GXP to Kingsland zone substation and have been in service since 1965, thus 54 years old. The 110 kV cables to Pacific Steel were installed in 1982 and the remainder of the fleet after that. The maximum practical life of subtransmission cables and their accessories is 90 years and our fleet is performing well and failures are rare. Strategy The 110 kV cable fleet will continue to be maintained as per our maintenance standard. Our CBARM model for this fleet is in progress and is scheduled for completion in FY19 which will further enhance our evaluation of this asset for the future. At present, there are no plans to replace any 110 kV cables but the network in the CBD will be extended as described in Section 5. 4.2.2 SUBTRANSMISSION 33 KV AND 22 KV UNDERGROUND CABLES Overview Key statistics of the 33 kV and 22 kV subtransmission feeder assets are shown in the table below. Due to legacy reasons, the data for cable joints are not 100% reliable, so quantities contain a level of estimation.
No of 33 kV underground subtransmission circuits
197
No of 33 kV circuits with undersea/underwaterway sections of subtransmission cables
7
Route length of 33 kV oil-filled subtransmission cable (km)
119
Route length of 33 kV paper insulated lead covered (PILC) subtransmission cable (km) Route length of 33 kV cross-linked polyethylene (XLPE) subtransmission cable (km) Route length of 33 kV subtransmission cable all types that are undersea or underwaterway (km)
17
282
12
No of 33 kV subtransmission cable joints
1516
No of 22 kV underground subtransmission circuits
72
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