Transend - Appendix 5 Renewal capital expenditure - Australian ...

4.3.2 TUNGATINAH SUBSTATION
The 110 kV voltage transformers installed at Tungatinah Substation include the following types:
� Haefely Trench VEOT 123 - three units (average age of 22 years);
� Ritz OTEF 123 - seven units (12 years); and
0BInvestment Evaluation Summary
TNM-GS-809-0720
� Trench SVS 123/3 - six units (9 years).
Between 1999 and 2003, a number of 110 kV voltage transformers (Brown Boveri TMZF and Asea Type EMFA) that
were in extremely poor condition were replaced to eliminate the likelihood of explosive failure and to sustain the
performance of the substation prior to the redevelopment of Tungatinah Substation 110 kV. The replacement units were
manufactured by Trench and are in acceptable condition. The Trench voltage transformers installed at Tungatinah
Substation will be redeployed elsewhere in the transmission network.
The average preventive maintenance costs associated with 110 kV voltage transformers at Tungatinah Substation is
$1,250 per three phase set.
Voltage transformers installed at Tungatinah Substation will be re-used in the redevelopment project or redeployed
elsewhere in the transmission system.
4.4 CURRENT TRANSFORMERS
The 110 kV current transformers installed at Tarraleah Switching Station comprise the following types:
� ABB type 236080 - nine units (average age of 13 years);
� Endurance Electric type OD-01-WP - six units (39 years); and
� Tyree type 06/123/16 - six units (30 years).
The 110 kV post type current transformers installed at Tungatinah Substation include three ABB type 236080 units
(average age of nine years).
In 1996, a number of Reyrolle 110 kV current transformers that were contaminated with polychlorinated biphenyl (PCB)
and in poor condition were replaced to ensure compliance with environmental legislation and to sustain the performance
of the substation. ABB type 236080 units were installed in place of the Reyrolle units.
The current transformers will be assessed for their suitability for redeployment elsewhere in the transmission network or
retained as spares.
The average preventive maintenance costs associated with 110 kV current transformers is $1,250 per three phase set.
4.5 POST INSULATORS
The 110 kV post insulators installed at Tungatinah Substation and Tarraleah Switching Station include:
� P640 units - 279 units installed at Tungatinah Substation; and
� P701A - 117 units installed at Tarraleah Substation.
The post insulators are a multi-piece construction that comprise individual insulators bolted together to achieve the
required voltage rating. The multi-piece design post insulators are susceptible to mechanical failure in certain operating
environments, such as those at Tungatinah Substation and Tarraleah Switching Station due to moisture freezing within
the post insulator, causing the porcelain components to crack. Transend has experienced a significant number of
mechanical and electrical failures of multi-piece post insulators over the past 10 years. The consequences of failure have
included an increased safety risk to personnel working in switchyards, considerable disruption to electricity supply and
the requirement for unplanned outages to facilitate replacement of post insulators.
The post insulator asset management plan (TNM-PL-809-0614) recommends the progressive replacement of multi-piece
post insulators.
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