Transcript Otara Gas Turbine Station

Otara Gas Turbine Station
By Doug St George, Assistant Engineer with
NZ Electricity Dept 1967 to 1969.
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This power station was built with 4 Stal-Laval gas
turbines, each of 50 Megawatts, or about 67,000
horsepower. The first turbine was dual-fuel, to run on
either Kapuni natural gas, or diesel and was cooled by
fresh water with cooling towers. Units 2,3 and 4 were
cooled by salt water from the Otara creek nearby.
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The turbine unit comprised a gas generator, on the left,
with separate low and high pressure compressors, twin
vertical combustion chambers, with piping above and
below the floor leading to the power turbine, driving the
generator. Starting was by compressed air blowing into
the low pressure compressor.
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The generator shaft had a free-wheel coupling to allow the
generator to be run at 3000 RPM on its own, as a
synchronous condensor, for voltage control.
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Some views follow, taken from the top of one of the
exhaust stacks. The Otahuhu Sub-Station building can
be seen, where remote start switches were fitted. The
turbines could be generating full power in a few minutes
after pressing start.
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A view of the Otara Creek, used for salt water cooling,
and the salt-water pumphouse.
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A view of the cooling towers for turbine # 1.
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The control room for the Otara Turbine Station.
In 1969, the equipment included relay control
panels and solid-state turbine governors, made
of discrete components (before integrated
circuits, silicon chips and computers were
invented)
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The NZED’s 1946
Bedford truck for use
by the Assistant
Engineers, Bob Eagle
and Doug St George.
We had use of it when
it was not being used
for blocking a hedge in
Henderson.
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After leaving the NZED
in 1969 I worked for
Stal-Laval in Sweden.
This is a picture of the
same type of turbine
installed in
Hämeenlinna, in
Finland. Others were
installed in China and
Västervik, Sweden.

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And now in 2007? In the
1970’s two more gas turbine
units were installed, but the
Government chose aeroengine types as they had
found the Stal-Laval units did
not start up reliably when
needed. Two more chimneys
were added to the western
end of the station. The
chimneys for the Stal-Laval
units have since been
removed.
Otahuhu B combined cycle
power station has been built
nearby.