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

0BInvestment Evaluation Summary
TNM-GS-809-0720
The average maintenance costs associated with 110 kV voltage transformers at Creek Road Substation is $1,250 per
three phase set.
4.5 CURRENT TRANSFORMERS
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. The in-service current transformers at Creek Road Substation include:
� ABB 236080 - 45 units (average age 13 years);
� Modern Products Drg. 039931 - six units (average age 34 years); and
� Reyrolle Drg. 015204 - nine units (average age 52 years).
The Reyolle units are in poor condition (high power factor) and utilise a silica gel breather that requires additional
maintenance. The Current Transformer Asset Management Plan (TNM-PL-809-0605) recommends that the Reyrolle
voltage transformers be replaced.
The ABB units will be assessed for their suitability for redeployment elsewhere in the transmission network following
their decommissioning as part of the redevelopment project. The Modern Products units will be retained as spares.
The average maintenance costs associated with 110 kV current transformers at Creek Road Substation is $5,500 per three
phase set.
4.6 POWER CABLES
A 70 metre nitrogen-filled 110 kV power cable connects the Chapel Street–Creek Road No. 2 110 kV transmission line
to its switching bay at Creek Road Substation. The cable was manufactured by Glover and Co. in 1959 and is single
core, gas-insulated design comprising copper conductor, paper insulation and an aluminium sheath. The cable is
susceptible to gas leaks and subsequent loss of gas pressure. Despite numerous attempts to address the issue, the cable
continues to leak nitrogen gas. The Power Cables Asset Management Plan (TNM-PL-809-0602) recommends that the
Chapel Street–Creek Road No. 2 110 kV power cable at Creek Road Substation be replaced in conjunction with other
planned capital works.
4.7 POST INSULATORS
The 110 kV post insulators installed at Creek Road Substation comprise:
� P1141 - 48 units;
� P640 units - 159 units; and
� P701A - 102 units.
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 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 EHV 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 multipiece
post insulators.
© Transend Networks Pty Ltd 7 of 17