Voltage regulators can be found both at the substation and out on distribution lines to help maintain a constant voltage level along the entire feeder. They are used especially on extra-long distribution feeders. Their operation is basically the same as that of substation regulators. They raise or lower the voltage on the distribution line to provide a more or less constant voltage as the amount of load on the line changes.
When the load on the line is low, the voltage drop is not very large and the customers near the end of the line have adequate voltage. When the load on the line is high, the voltage drop is also higher and customers near the end of the line may experience low voltage. Voltage regulators automatically adjust to these low and high load situations to assure all customers have proper voltage to run their electrical equipment.