What is the main purpose of the load tap changer (LTC)?

The primary purpose of a load tap changer (LTC) is to adjust the transformer’s voltage level while the transformer is in service, specifically by modifying the number of active turns in the transformer winding. This is crucial in ensuring that the voltage output remains stable regardless of variations in load conditions. The LTC achieves this by tapping into different turns of the transformer winding, effectively altering the transformer’s turns ratio.

By doing so, the LTC can respond to changes in load and maintain the desired voltage level within the specified range. This operation is essential for ensuring efficient power distribution and preventing issues like overvoltage or undervoltage that could harm equipment or affect service quality.

While other options mention important functions in an electrical system, they do not capture the specific and critical role of an LTC in managing and regulating voltage through adjusting the transformer's winding configuration.