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4.2 VOLTAGE TRANSFORMERS
The 110 kV voltage transformers at Palmerston Substation comprise the following types:
� ASEA type EMFA120 (six units);
0BInvestment Evaluation Summary
TNM-GS-809-0720
� Ducon type PD-AS-11AB (three capacitor voltage transformer units and one coupling capacitor unit); and
� Reyrolle type KP5323 (one unit).
ASEA voltage transformers
The ASEA type EMFA 120 110 kV voltage transformers in service at Palmerston Substation were manufactured in
1963. Voltage transformers of this type have failed explosively in the past. The explosive failure of a voltage transformer
presents a significant safety risk to anyone in the vicinity of the voltage transformer at the time of failure. There is also a
significant risk of adjacent assets being damaged or destroyed as a consequence of an explosive voltage transformer
failure.
The average annual preventive maintenance costs associated with 110 kV voltage transformers at Palmerston Substation
are $5,500 per three phase set.
The EHV Voltage Transformer Asset Management Plan (TNM-PL-809-0614) recommends that the ASEA type
EMFA 120 110 kV transformers at Palmerston Substation be replaced because they are in poor electrical condition, are
susceptible to major failure and are an obsolete design. The ASEA EMFA 120 110 kV voltage transformers will be
51 years old when decommissioned.
Ducon voltage transformers
Ducon 110 kV voltage transformers are approaching the end of their service lives, have inherent design deficiencies and
are susceptible to explosive failure. Transend has experienced explosive failures of Ducon 110 kV voltage transformers
at Palmerston Substation in 2001 and at Avoca Substation in March 2008. Figure 3 presents an image of a failed Ducon
110 kV voltage transformer and porcelain fragments in the switchyard.
© Transend Networks Pty Ltd 6 of 13