Hydro Power-ful

Waddamana Power Station Heritage Site

Everyone knows that Tasmania gets a lot of rain – especially up in the mountainous centre of the island. When we’ve seen a waterfall with the tremendous roar of water racing down, you can imagine that a lot of energy is available do useful work – and that’s where hydro power comes in.

Waddamana power station is an old power station which started up way back in 1915 (that’s over 20 years before the hoover dam in the USA). It was built to provide power for processing minerals like Zinc and Carbide further south in Tasmania. It was the first hydro power plant built in Tasmania, and now there are loads more in the state, which make lots of power without burning any gas or coal (yay!). Tasmania even sends clean power over to mainland Australia via the Basslink power cable that runs on the ocean floor under Bass Strait.

Waddamana is in a remote location in Central Tasmania, and since it’s only accessible via dirt road, doesn’t get as many visitors as it should. Nevertheless, it’s worth the effort and makes a great side trip when going between Launceston and Hobart. In fact it’s thanks to it’s very remoteness that the power station was preserved. It was just too difficult to remove the heavy equipment through the rough terrain in the area, so they just left it all in place, rather than sell it for scrap!

The complex consists of a number of different parts: the turbine hall, the penstocks, the control room and the town built to service those who worked at the plant.

The Penstocks

In a hydro electric power plant, the pipes that connect the water at a dam at the top of a hill to the power plant are called Penstocks. You can see the pipes coming down the hill in the photo below. The weight of the water pushing down the hill is what gives the energy to the power plant, and by the time the water reaches the bottom of the hill, it’s got a lot of pressure ready to do useful work making electricity.

Waddamana Power Station Heritage Site – note the water pipework that comes down from the adjacent hill (penstocks)

The Turbine Hall

Big Butterfly Valve – Waddamana Power Station. The blue part of the valve swings back and forth when it’s opened and closed to block or open the flow of water. The valve is easily big enough to crawl through!

The real business end of the operation is inside the turbine hall, and this is the most interesting part of the site. This is where the high pressure water from the big pipes is released onto the hydraulic turbines. The great thing about Waddamana is that some of the equipment is opened up so you can see what happens inside these big machines. The yellow and orange buckets in the picture below are what the water is jetted onto which turn the whole machine. The turbine is connected to the generator via a shaft and this makes electricity. You can also see the inside of the generator, with massive windings of copper wire for the different parts (the stator and the rotor).

Waddamana Power Station Heritage Site

The inside of an electric generator looks complicated, but there are really two parts – the stator and the rotor. Making electricity is all about movement between a magnetic field and a wire (or lots of wires).

The rotor is the bit that’s rotating (coloured red in the picture below) and is turned by the hydraulic turbine. The rotor has electric windings to set up a magnetic field. The magnetic field is created by electro magnets with a small voltage (called the excitation voltage), which is carefully controlled.

The stator is the bit that’s stationary, so doesn’t spin. This is the outside bit, and consists of lots of wires that have a magnetic field that moves over them and makes electricity. It turns out that the stronger the magnetic field, the higher the voltage that’s created, so controlling the excitation voltage is very important for a power plant.

The inside of the generator. Normally all of this would be covered up since it would be spinning really fast and have dangerous voltages inside, so it’s really cool to be able to see inside

The buckets that the water hit slowly get worn out by the water jetting onto it and so need to be repaired over time. At the plant, they used to fix them up by opening up the turbine, un-bolting them and putting a weld patch on them.

The water flowing onto the buckets is controlled via a valve that opens up when more power is required. The valve consists of a hole with a sort of shaped needle inside it. If the needle is pushed down into the hole, then it blocks the flow, but if it’s pulled back, then the water flows around the needle in a nice smooth shape, then smacks into the bucket and pushes the turbine around and around.

Turbine buckets and the valve that releases the water into them.
Waddamana Power Station Heritage Site – the turbine hall

Control Room

The control room is where the plant used to be operated. The operators could see what was happening on the grid and adjust the amount of power that the plant supplied. They could also turn off one of the generators if it wasn’t required, or bring one on if more power was required. Normally power demand would go up and down at particular times of day as industrial or other consumers would start up or finish for the day. Since it’s very old, there are no computers, but instead loads of nobs and dials. The interesting thing is that making hydroelectric power hasn’t changed that much over the years, it’s still a matter of passing that water through a turbine and spinning a generator. In the control room they can make sure the power plant is providing the right voltage and frequency to the grid. Frequency is the rate at which the current and voltage supplied by the plant cycles up and down, and this needs to be kept at 50 cycles per second (50 Hz). They have a clock which measures this and if the frequency is a little slow, then the clock starts to read a little slow, so then they nudge the frequency up a little bit using one of the many nobs that control the generators. Simple but effective!

The control room is behind these beautiful wooden windows on the top level, with a great view out over the turbine hall
Waddamana Power Station Heritage Site – Control Room
Waddamana Power Station Heritage Site – control room

electrical Stuff

Once the plant has made power, then it needs to get to the end users. That means lots of wires and transformers and switches.

Outside of the powerplant there are some massive power lines and large transformers. The power lines carry the power and the transformers increase the voltage of the power (higher voltages mean that less of the energy is lost as it goes through the power lines).

The electricity is switched on and off using big switches like in the picture below. They call them breakers because they break the current when they’re open. These really old ones have wooden doors and glass windows so you can see inside. Breakers are not so different to a light switch you use at home, except they’re much bigger! Breakers are important safety features of a power plant, since they open up if something goes wrong and hence prevent things getting very bad (electrical faults cause nasty fires or explosions).

Circuit Breakers on a generator. The read motor on the top winds up a spring so that if required the breaker can open really quickly if something goes wrong

In the 1960’s, the plant was shutdown and replaced with another hydro power plant which was three times as powerful. If you are in Tasmania, this is a really cool, interesting and informative place to visit.

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