Tertiary Winding in Power Transformers: Uses and Applications

A tertiary winding in a power transformer is an extra winding, distinct from the primary and secondary windings. In essence, a power transformer has a primary winding connected to the input voltage and a secondary winding connected to the output voltage. The tertiary winding, when present, acts as a third winding that’s electrically isolated from both the primary and secondary windings.

The tertiary winding fulfills various roles, tailored to the specific needs of the power system and the transformer’s designated application.

Uses of a Tertiary Winding

Here are some typical uses for a tertiary winding:

• Voltage Regulation and Stabilization: The tertiary winding can be used to offer enhanced voltage control and regulation. By tweaking the voltage across the tertiary winding, we can improve the transformer’s overall voltage regulation.

• Harmonic Mitigation: Tertiary windings can be used to suppress or mitigate harmonics present in the transformer’s output voltage. This is particularly important in systems where minimizing harmonic distortion is crucial for the proper operation of sensitive equipment.

• Zero-Sequence Current Path: The tertiary winding can provide a pathway for zero-sequence currents. Zero-sequence currents are currents that flow in the neutral of a three-phase system. The tertiary winding aids in balancing and provides a low-impedance path for these currents.

• Fault Current Limiting: Tertiary windings can be designed with specific impedance characteristics to limit fault currents within the transformer. This helps safeguard the transformer and the connected system in the event of a fault.