A pump-storage power plant, such as an electric unit, for this purpose can include a rotating electric synchronous machine and a frequency converter as well as a method for operating the electric unit. An exemplary method provides that the frequency converter is used to start the turbine and an output of the electric machine is fed directly into the current network after start-up, for example. Another exemplary method provides that the frequency converter is used to start the pump and the pump is started directly from rest and under load of a flooded pump or a water column, for example. Another exemplary method provides that the electric machine is synchronised with a frequency of the current network and is operated synchronously with the current network independent of the operating state of the pump or the turbine and supplies active power and reactive power.