An AVR, or Automatic Voltage Regulator, is an electronic device used in generators to automatically regulate voltage. It is part of the generators excitation system, which is designed to build the voltage at starting and stabilize it at a preset level during the generators operation. The AVR continuously monitors the voltage at the main stator terminals and adjusts the excitation to maintain a constant output voltage, even when the load or operating temperature changes. Without an AVR, voltage can sag, spike, or surge, which can damage electrical devices. The AVR is an integral part of the alternators excitation system and directly correlates to the performance and longevity of the generator, as well as the items that the generator is providing power to.