A tap changer is a device used in transformers to vary the turns ratio of the transformer winding, which ultimately changes the voltage ratio between the primary and secondary sides of the transformer. This adjustment is necessary to regulate the output voltage and compensate for variations in the input voltage and load conditions.
In power systems, it is essential to maintain a constant voltage level to ensure proper functioning of electrical equipment. However, the input voltage from the power grid can fluctuate due to factors like load changes, line losses, or variations in the power generation. To address this, transformers are equipped with tap changers to modify the number of turns in the winding, allowing for voltage adjustments.
There are two primary types of tap changers:
On-Load Tap Changer (OLTC): An On-Load Tap Changer is designed to change the transformer's tap position while the transformer is energized and supplying power to the connected load. This type of tap changer is used in power transformers and voltage regulation applications where the load and voltage conditions change frequently. OLTCs enable dynamic control of the output voltage, allowing the transformer to respond to changing system conditions.
Off-Circuit Tap Changer (OCTC): An Off-Circuit Tap Changer is intended for changing the tap position only when the transformer is de-energized. This type is commonly used in distribution transformers or applications where power interruptions during tap changes are acceptable. Unlike OLTC, OCTCs are not suitable for continuous voltage regulation during transformer operation.
The tap changer typically consists of a selector switch, a diverter switch, and a set of tap positions. The selector switch is used to change the tap