Choose the INCORRECT statement with respect to synchronous machines.
1. The rotating air gap field and the rotor in the machine rotate at the same speed.
2. The power factor of the machine is always closer to 0.9 lag at any condition.
3. It runs at a constant speed at steady state when it is connected to fixed supply with variable load.
4. The rotor poles are excited by a DC current, and its stator windings are connected to an AC supply.