Tumut 3 Power Station - NSW

T3 is the largest of the Snowy Schemes 7 major power stations. Completed in 1972 with six 250 MW generators giving the 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 produce 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 tailbay turbulence shows. An old runner is on display next to a pump impeller.

Units 4,5 and 6 have undercoupled pumps. These three generators can reverse and consume 200 MW of power to now be motors and thereby pump water back up through a head of 155 m each at a rate of 99 cumecs. This power is purchased at cheaper off-peak rates. 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.