Papers [1] and [2] focused on governor fundamental speed control basics; the focus of this paper is a fundamental understanding of Automatic Voltage Regulator [3] basics for voltage control and MVAR load sharing. Discussions focus on non-complex, islanding applications for upstream oil and gas and downstream petrochemical facilities, such as, large motor starting, gas turbine step load capability after mechanical tripping of an online generator, load shedding to preserve continued system operation, and electrical protection philosophy basics to maintain system stability.