There are three main methods used to control the voltage at the end of a distribution feeder – By using control equipment to vary the voltage at the supply end of the feeder or at the load end and by controlling the current in the line by changing the power factor. Uni-Directional – They can only change the voltage on the load-side of the regulator and have no effect on the source-side. They are installed in series between the Source and Load. They are a voltage source, they add or subtract. Installation Select an appropriate location: It is usually installed inside the distribution box, close to the power inlet side, in a place that is convenient for installation and maintenance. For single row 20, and circuit 24, fter confirming the wires meet the requirements. Close ormal operation due to poor manufacture quality. Voltage Regulators Used Control.