ZPfC (zero power fact or characteristic) of a synchronous

ZPfC (zero power fact or characteristic) of a synchronous generator is obtained by performing

1. generator is loaded to give varying zero pf lagging current while its excitation is adjusted to give the rated terminal voltage.
2. generator is loaded to give varying zero pf leading current while its excitation is adjusted to give the rated terminal voltage.
3. generator is loaded to give rated zero pf leading current and its excitation is adjusted to vary the terminal voltage
4. generator is loaded to give rated zero pf lagging current and its excitation is adjusted to vary the terminal voltage.