Transformer tap changers are devices used to adjust the turns ratio of a transformer, thereby changing the output voltage to match varying load conditions or to compensate for voltage fluctuations in the supply system.
There are two common types of tap changers:
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On-Load Tap Changers (OLTC): These tap changers can change the transformer's turns ratio while it is energized and under load. OLTCs are often used in applications where the load or the primary voltage may vary significantly, such as distribution networks and industrial facilities.
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Off-Circuit Tap Changers (OCTC): These tap changers require the transformer to be de-energized to make any tap adjustments. They are commonly used in applications where the load variations are less frequent or in smaller distribution transformers.
Tap changers typically have multiple tap positions, each representing a different turns ratio and corresponding output voltage. By adjusting the tap selector, the transformer's output voltage can be varied to match the desired or required voltage levels.
The number of tap positions depends on the design and capacity of the transformer, and the range of voltage adjustment varies based on the specific tap changer configuration. The tap changer is an essential component in ensuring that the output voltage of the transformer remains within acceptable limits, even under varying load and supply conditions.