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

4.1 CIRCUIT BREAKERS
0BInvestment Evaluation Summary
TNM-GS-809-0720
The 110 kV circuit breakers (three units) installed at Meadowbank Substation are Reyrolle type 110/OS/10 units. The
Reyrolle Type 110/OS/10 110 kV Circuit Breaker Condition Assessment Report (TNM-CR-806-0772) assesses the
condition of Reyrolle type 110/OS/10 circuit breakers and recommends that the units at Meadowbank Substation be
replaced. The circuit breaker assessment has been based on key asset management considerations, including technical,
design, reliability, condition, maintenance, spares and contingency planning, life-cycle and environment issues. The
condition assessment report provides details of the many failures and defects associated with Reyrolle 110 kV circuit
breakers, including those installed at Meadowbank Substation. The condition assessment report has identified that the
Reyrolle type 110/OS/10 circuit breakers:
� have a number of inherent technical and design deficiencies that have adversely impacted transmission circuit
reliability and availability;
� are unreliable, in particular the air and insulating oil systems;
� are maintenance intensive and costly to maintain when compared with modern equivalent units;
� require spare parts that are no longer available from the manufacturer’s agent;
� require skilled personnel to maintain - the availability of specialised maintenance resources is declining; and
� have reached the end of their useful service lives.
All other transmission companies in Australia and New Zealand have already replaced their population of Reyrolle type
110/OS/10 circuit breakers, or are in the process of doing so, for the same reasons outlined above. Transend’s reasons for
replacing this type of circuit breaker are no different to those of other industry participants.
The 110 kV circuit breakers at Meadowbank Substation will be 52 years old when decommissioned, and will have
exceeded their assigned class life of 45 years as defined by Sinclair Knight Merz in its Assessment of Economic Lives
for Transend Regulatory Classes, April 2008.
The preventive maintenance costs associated with the 110 kV circuit breakers at Meadowbank Substation include:
� circuit breaker maintenance: $8 300 per circuit breaker (six yearly);
� insulating oil costs: $4 200 per circuit breaker (six yearly);
� compressor maintenance: $1 000 per compressor (six-monthly for the compressor at Meadowbank Substation);
� silica gel maintenance: $500 per circuit breaker (two yearly); and
� pressure inspection costs: $300 per circuit breaker (three yearly).
� In addition, the average historic repair cost for a failure or defect associated with a Reyrolle type 110/OS/10 circuit
breaker is $4 730.
Further information on the circuit breaker population can also be found in the Extra High Voltage Circuit Breaker Asset
Management Plan (TNM-PL-809-0541).
4.2 VOLTAGE TRANSFORMERS
The 110 kV voltage transformers installed at Meadowbank Substation comprise the following types:
� Balteau type UEV110 - 3 units (average age of 30 years); and
� Ducon type PD - 2 units (45 years).
Balteau voltage transformers
The Balteau type UEV110 voltage transformers have a number of design deficiencies, including:
� the design is susceptible to moisture ingress. Instances of moisture ingress through the diaphragm have occurred,
which has resulted in the high percentage power factor readings of other Balteau units installed in the transmission
network;
� a poorly designed oil-level sight glass. The sight glass is susceptible to mechanical failure and vandalism. The
failure of a sight glass will allow moisture to enter the expansion chamber and pool on the rubber diaphragm. It is
extremely difficult to assess the integrity of the sight glass with the voltage transformer in service; and
� units do not have oil-sampling facilities.
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