The AVR senses the voltage on the main generator winding either directly or via transformers. This signal is used to control the power fed to the exciter stator (and hence the main rotor) to maintain the generator output voltage within the specified limits, compensating for load, speed, temperature and power factor. Three phase RMS sensing is employed for superior voltage regulation. Provision is made for the connection of a remote trimmer allowing the user fine control of the generator output voltage.

Soft-start circuitry is included to provide a smooth controlled build up of generator output voltage. A frequency measuring circuit continually monitors the speed of the generator to provide protection of the excitation system. This operates by reducing the generator output voltage proportionally with speed below an adjustable threshold. A further enhancement of this feature is an adjustable ‘volts per Hertz’ slope (dip) and a delayed voltage recovery (dwell) both designed to improve speed recovery time when the generator is used in conjunction with turbo-charged engines