The AVR, or automatic voltage regulator, is a small device that’s located on the alternator. Its job is to monitor the power output. These very small devices will work hard to maintain the electrical output terminal voltage. This type of device is more commonly found on diesel generators and ensures that the required level of power remains constant. Without an AVR, the amount of power the generator produced would not be consistent. You’ll know the AVR on your generator is working fine if your generator is functioning correctly. If the AVR isn’t working, you’ll notice right away as the generator’s engine begins to struggle to maintain a consistent level of power.