sentences:  Often hydroelectric power plants are designated as the black-start sources to restore network interconnections.A hydroelectric station needs very little initial power for starting purposes (just enough to open the intake gates and provide excitation current to the generator field coils), and can put a large block of power on line very quickly to allow start-up of fossil-fuel or nuclear stations.Certain types of combustion turbine can be configured for black start, providing another option in places without suitable hydroelectric plants.