Voltage Regulators & TCUL

Distribution Line Voltage Regulators Picture Voltage regulators do just what their name implies, regulate the voltage. The voltage along a distribution line changes with the amount of load being drawn by customers. When the load is high, the voltage may drop too low.

If voltage is to be regulated in the substation, the most economical method is with tap changing under load (TCUL), sometimes referred to as LTC or load tap changing, built into the transformer. (TCUL) Picture The low voltage, or secondary, winding of a transformer with TCUL is built with several tap settings allowing the secondary windings to be adjusted based upon the desired voltage level. These taps are connected to a fully automatic tap-changing mechanism. Its operation is controlled by the voltage on the secondary side of the transformer.

By properly setting the controls, the tap changer will automatically raise or lower the transformer's output voltage to maintain a constant voltage at some pre-selected point out on the system.

Occasionally there will be regulators both at the substation and out on the line. Various conditions like amount of load and length of the line influence such placement.