The synchronous generator is started up and stopped with a frequency-controlled electric motor (pony motor) or a starting frequency converter.
When the generator has reached operating synchronous speed depending on the system frequency, it will be synchronized with the transmission network, and the machine is operated as a motor providing reactive and short-circuit power to the transmission network.
Synchronous electrical machines, like synchronous generators can generally be used as synchronous condensers. Without active power delivery (or consumption) the machines can act like a capacitor or like a reactor, depending on the excitation field current.