AVR R726 is a half-wave phase controlled thyristor type Auto Voltage Regulator and forms part of the excitation system for a brushless generator. 
In addition to regulating the generator voltage, the AVR circuitry includes under speed and sensing loss protection to ensure safe, reliable control of the generator. 
Positive voltage build up from residual levels is ensured by the use of proficient semiconductors in the power circuitry of the AVR. Which is linked with the main stator windings and the exciter field windings to offer closed loop control of the output voltage with load regulations of +/- 1.5%