Automatic Voltage Regulator

An Automatic Voltage Regulator (AVR) is a device that regulates the voltage. It takes fluctuating voltage and changes it into a constant voltage. The fluctuation in voltage mainly occurs due to the variation in load on the supply system. The AVR works on the principle of error detection. The output voltage of an AC generator is obtained through a potential transformer, then it is rectified, filtered, and compared with a reference. The difference between the actual voltage and the reference voltage is known as the error voltage. This error voltage is amplified and then supplied to the main exciter or pilot exciter. Thus, the amplified error signals control the excitation of the main or pilot exciter through a buck or a boost action (i.e., controls the fluctuation of the voltage). Exciter output control leads to the control of the main alternator terminal voltage.

The main functions of an AVR are:

  1. It controls the voltage of the system and has the operation of the machine nearer to steady-state stability.
  2. It divides the reactive load between the alternators operating in parallel.
  3. The automatic voltage regulators reduce over voltages which occur because of sudden loss of load on the system.
  4. It increases the excitation of the system under fault conditions so that maximum synchronizing power exists at the time of clearance of the fault.
  5. In terms of applications, AVRs are used in generators with the purpose of automatically regulating voltage, which means that it will turn fluctuating voltage levels into constant voltage levels. They also serve as a buffer for voltage fluctuations, delivering a reliable flow of power at all times.
Industries Served
  • Industrial
  • Power Distribution
  • Marine
  • Power Generation
  • Commercial
Typical Applications
  • Voltage Regulation and Excitation Control of Rotary or Static Excited Machines
  • Prime Power Generator
  • Utility Power Generation
  • Standby Genset
  • Synchronous Motor
  • Synchronous Condenser
  • Pump Storage Generator
Protection and Control
  • Feeder
  • Generator
  • Intertie
  • Transformer
  • Motor
  • Bus
  • Breaker
Control of Generator Sets
  • Emergency Standby
  • Prime Power
  • Peak Demand
  • Portable
  • Combined Heat and Power

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