Should a no load tap changer on a transformer be adjusted while it is energized to change voltage?

The question focuses on whether a no-load tap changer on a transformer can be adjusted while the transformer is energized to change voltage. The correct answer is that it should not be adjusted while energized, emphasizing safety and operational integrity.

A no-load tap changer is designed to change the transformer's turns ratio when there is no load on the secondary side, meaning the transformer is not supplying power to any significant load. Adjusting a tap changer while the transformer is energized can lead to electrical arcing and potential damage to both the tap changer and the transformer, as it may disrupt the current flow. Additionally, inappropriate adjustments could create unsafe conditions for operators and equipment. Therefore, such adjustments are recommended to be performed only when the transformer is de-energized to ensure worker safety and to maintain the lifespan of the transformer equipment.

Understanding that tap changers are typically used in scenarios where the voltage needs to be adjusted without disconnecting from the grid further illustrates why these adjustments should only be made safely and deliberately, aligning with established industry practices for transformer management.