Correct Answer - Option 1 : Load
- Power factor of the alternator defines the phase angle between the current drawn and applied voltage.
The power factor of the alternator depends upon the type of load. In case if it is an infinite bus, then the power factor of the alternator depends upon the excitation of the alternator.
- According to load, the alternator provides both reactive (kVAR) and real power (kW).
- When the load is RL type it requires lagging VAR and that power has to be provided by the alternator.
- When the load is of RC type, it requires leading VAR, and that power is provided by the alternator.
The effect of armature (stator) flux on the flux produced by the rotor field poles is called armature reaction. It depends on the power factor i.e. the phase relationship between the terminal voltage and armature current.
- The armature reaction flux is constant in magnitude and rotates at synchronous speed
- At unity power factor load, the armature reaction is cross-magnetizing (distortional)
- At lagging power factor load, the armature reaction is partly demagnetizing and partly cross-magnetizing; At zero power factor lagging load, it is purely demagnetizing and the induced emf will get decreased
- When the generator supplies a load at leading power factor the armature reaction is partly magnetizing and partly cross-magnetizing; At zero power factor leading load, it is purely magnetizing and the induced emf will get increased