For what reason should all covers be in place before power is applied to the transformer?

Applying power to a transformer with all covers in place is fundamentally about ensuring the safety of personnel. Transformer components can have high voltage and current levels, and exposing those components can lead to potentially dangerous situations, such as electric shock, arc flash, or other hazards. Ensuring that all covers are securely in place acts as a protective barrier, reducing the risk of accidental contact with live parts for anyone working near the transformer or performing maintenance.

While maintaining equipment integrity, preventing water ingress, and adhering to manufacturer guidelines are also important considerations, the primary reason for ensuring that covers are in place before applying power is to prevent harm to individuals who might be nearby. By prioritizing safety, you help create a secure work environment and reduce liability risks.