Automatic Voltage Regulator of Alternator


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Automatic Voltage Regulator of Alternator:

  • It is important part in Synchronous Generators; it controls the output voltage of the generator by controlling its excitation current. Thus it can control the output Reactive Power of the Generator.
  • AVR increases or decreases exciter current for a more linear voltage and frequency.
  • It is a device used to maintain a constant voltage at the Alternators terminals. It functions by maintaining the Excitation required maintaining the terminal voltage of the Alternator with change in the load.
  • Increase in excitation voltage increases reactive volt-ampere (KVAR) which decreases power factor (cos (φ)).
  • Generally, voltage (V) of the alternator is kept constant so the rest of the components in VICos (φ), i.e. I and Cos (φ) have to vary according to the load.
  • Increase in I causes decrease in Pf and Decrease in I causes increase in Pf. so it is clear that Excitation V is proportional to KVAR and load current (I) and inversely proportional to power factor Cos(φ)) Increase in excitation voltage increases reactive volt-ampere (KVAR) which decreases power factor (Cos (φ)).