Nicole Cleary photo via The Age

On the trail

The massive pylons and quad bundle conductors look just like those on the 500 kV twin circuit Moorabool-Portland transmission line I wrote about the other month.

I’ve been a fan of this transmission line for years.

The lush green grass suggested dairy country around Mortlake, not the wheat fields of the Pleurisy Plains.

But there was one big clue – the pair of transposition towers in the background.

A transposition tower is a transmission tower that changes the relative physical positions of the conductors of a transmission line in a polyphase system. A transposition tower allows these sections to be connected together, while maintaining adequate clearance for the conductors. This is important since it distributes electrical impedances between phases of a circuit over time, reducing the problem of one conductor carrying more current than others.

Double-circuit lines are usually set up with conductors of the same phase placed opposite each other. This reduces the reactance due to mutual inductance; the reactance of both circuits together is less than half that of one circuit. For example, a section of a line may be (top-to-bottom) phases A-B-C on the left, also phases C’-B’-A’ on the right. The next section may be B-C-A on the left, also A’-C’-B’ on the right. Therefore, the rotation on each side of the tower will be opposite.

But would a set of transposition towers be big enough to spot on Google Maps?

And away I go

My initial theory was that the photo couldn’t be taken *that* far from Melbourne or off a main road – normal people don’t go driving for hours down bush tracks just to photograph power lines – so I made a virtual visit to the Moorabool Terminal Station outside Geelong.

Google Maps

My first location of note on Google Maps – a hub of activity outside Cressy, where the transmission lines were being repaired.

Google Maps

Six pylons came tumbling down to earth in January 2020 following extreme winds.

ABC News photo

The outage shut down the Portland aluminium smelter, until temporary repairs were completed to allow power to be restored.

The Standard photo

Then off across empty plains until Lismore – where I found two parallel single circuit pylons.

Google Maps

But this wasn’t the transposition towers I was looking for, but somewhere I’ve been meaning to visit in person – the spot where the 500 kV line crosses over the single circuit Ballarat to Terang 220 kV line.

Google Street View

As I continued west, the paddocks started to turn green, and I found another place I’m yet to visit – Mortlake Terminal Station.

Google Maps

And the fossil gas fired Mortlake Power Station that relies on it.

Origin Energy photo

And finally something that matched what I was looking for – a pair of single circuit transposition towers in the middle of a twin circuit transmission line, outside the locality of Willatook.

Google Maps

Following Google Street View along Malseeds Road found the transposition towers.

Google Street View

But given the transmission line turns to the right before reaching the transposition towers, I needed to head west – Willatook-Warrong Road was the next road to take.

Google Street View

Now to see if it was the same set of pylons.

Nicole Cleary photo via The Age

And boom .

Google Street View

A match!

And one last detail

The little sign in the background of the original photo looked like a ‘Danger: Gas Pipeline’ sign, but the only gas network diagrams I could find lacked sufficient detail to confirm.

AEMO gas pipeline network map

And over at Open Infrastructure Map the only feature at the location was the 500 kV transmission line I’d been following since Moorabool.

Open Infrastructure Map

So an adventure for another day.

Further reading

Some more detail on the 2020 transmission line pylon collapse at Cressy.

• AEMO Preliminary Report – Victoria and South Australia Separation Event – April 2020
• AusNet Services cost pass through application – July 2020
• Energy Safe Victoria incident report – November 2020

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Trains

It isn’t a road trip if I wasn’t trying to photograph trains!

We’d been driving for a few hours before we passed out first one – a loaded grain train bound for Geelong.

A few hours later we found an empty grain train headed back west for another load.

Shortly followed by a load of containers headed the other way for Melbourne.

And then on our way home, a load of steel beams and plate.

Abandoned stations

The only passenger service along the line is twice weekly The Overland, which runs through without stopping.

Inverleigh is just a timber shed.

As is Pura Pura.

At least Westmere still has grain silos.

And Maroona has a disused platform.

And abandoned towns

The Pleurisy Plains are grain and grazing country, and the townships that did exist have been emptying out.

There was nothing much to see at Nerrin Nerrin.

Mininera Primary School is long gone.

Westmere once had a general store, but it’s for sale.

And Streatham – it’s still got an Infant Welfare Centre, but only open two mornings each month.

Wind farms

Windy plains are good for one thing – wind farms.

80 turbines at the Dundonnell Wind Farm north of Mortlake.

75 turbines at the Ararat Wind Farm.

Just two at the Maroona Wind Farm.

And 43 turbines at the Berrybank Wind Farm, with another 26 being added.

Power lines

The power generated by wind farms has to go somewhere, so high voltage transmission lines cross the otherwise empty plains.

The big one is the 500 kV twin circuit Moorabool – Portland line, constructed in the 1980s to transmit electricity generated from burning brown coal to Alcoa’s aluminium smelter at Portland.

The oldest is the single circuit Ballarat to Terang 220 kV line.

But they’ve recently been joined by the 132 kV line that links the Stockyard Hill Wind Farm to the Haunted Gully Terminal Station.

Which passes beneath the older 220 kV line via a tangle of pylons outside Lismore.

Telephone exchanges

In the days before mobile phones, copper wires were the only communication link to the outside world.

Maroona has a telephone exchange not much larger than the outdoor dunny beside it.

As does Nerrin Nerrin.

Berrybank has a shed a little larger.

Streatham’s exchange is bigger again, but it serves an actual town.

But Pura Pura – there is nothing around for miles!

CFA stations

Even with the population leaving the plains, the risk of bushfire is still there.

The CFA station at Nerrin Nerrin is just a little tin shed.

The station at Mininera is far more modern.

As is the one at Langi Logan.

Which replaced the tin shed around the corner.

And finally – Mount Elephant

Every time I’ve gone for a trip on The Overland I’ve pointed out Mount Elephant – a 380-metre-high conical breached scoria cone formed by a dormant volcano, located 1 km from the town of Derrinallum. So since I was in the area, I paid a visit.

Turns out it’s only open for a few hours each Sunday, but I was lucky – they were just about to open!

The visitors centre is located at the base of the mountain.

The access track follows the alignment of a dismantled railway siding.

Which served a ballast quarry, now used as a car park.

The walk to the edge of the crater takes 30 minutes, with the walk around the edge adding an extra hour.

But since it was a stinking hot day, we only made it halfway up.

So we’ll have to visit again!

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