Tumut 3 Power Station - NSW

Tumut 3 is the largest of the Snowy Schemes 7 major power stations. Upon completion in 1973 the six 250 MW generators gave the T3 station a rating of 1500 MW. A headrace channel directs water to the 6 steel pipelines. Every second 188 cumecs of water - that's 188 tonnes - enters a pipe. It falls 150 m and it's gravitational potential energy is converted into the kinetic energy as the water moves down the pipe into the spiral casing of the turbine. Here the linear motion pushes on the 17 blades of the turbine runner to spin it at 187 rpm and thus produces rotary motion. The water exits via the draft tube into the tailbay to flow into Jounama Pondage.

A stainless steel shaft connects the turbine to the generator several stories above and the output is AC power. A six year upgrade ending in 2012 has lifted the station capacity to 1800 MW with installation of new technology turbine runners with forward leaning blades which capture more of the water's energy. But not every last bit as the tailbay turbulence shows. An old spare runner is on display next to a pump impeller.

Units 4,5 and 6 have undercoupled pumps connected by a shaft. The generators still spin clockwise as seen from above but now each consumes 200 MW of power to now act as motors. The pump impeller spins and creates a low pressure area at its centre, drawing water in from the tailbay. The 7 vanes push water outwards at a high pressure and it flows back up the penstock up through a head of 155 m at a rate of 99 cumecs per pump. This power is purchased at cheaper rates such as when there is a surplus of solar or wind energy. The same water is used at the next peak period earning Snowy Hydro many times the cost price. This is the principle behind Snowy 2.0.

Closed to the public for interior tours.