Limberg 3 construction site: mighty machine parts have arrived

Weighing 91 tonnes and measuring 10 metres in length: that’s the shaft that transfers the power of the water to the turbines of Limberg 3. The hall cranes lifted the gigantic steel pin was lifted into position centimetre by centimetre. It is critical that the personnel have a sensitive touch, strong nerves and good coordination.

Following completion of the excavation work in the power plant cavern of Limber 3, the space inside the mountain is rapidly filling up. Concrete is being poured floor by floor. Special transports bring the might machine parts into the underground power plant construction site through the 5.5 kilometre-long tunnel.

The ribbed shaft of the generator is especially challenging. This 91-tonne part is transported horizontally, but has to be raised on end and inserted into the appropriate tipping device. The generator ribbed shaft is the “blank” of the rotating part of the motor generator. The rotary motion turns hydropower into electrical power – with a capacity of 240 megawatts (MW). That corresponds to the power of about 50 large wind turbines. The rotor first has to be coated, after which it has a mass of 370 tonnes, making it the heaviest single lift on the entire construction site. The shaft needs a suitably rugged design to be able to withstand these gigantic loads. With a breathtaking 550 revolutions per minute, the machine is faster than any racing car. And it needs to be because the pumped storage power plant should not only store excess electricity for the winter, but also be able to intervene in a matter of seconds to even out any voltage fluctuations.

Key component: the ribbed shaft

The delivery of the ribbed shaft represents a big step forwards for the strategic schedule. While concreting work can carry on for machine 2, the assembly and completion of the remaining components for machine 1 can already be started. The goal of the ambitious schedule is to commence operation by 2025.