While standing an "at sea watch" onboard a modern rectified DC diesel-electric drive ship you notice the transformer core temperature slowly rising. What should be your FIRST action?

Correct Answer: Option B — check the transformer ventilation fans for proper operation

Transformer operating temperatures directly correlate to cooling efficiency and core losses. When core temperatures rise abnormally during a watch, verifying ventilation fan operation is the immediate corrective action required to restore proper forced-air cooling before thermal damage occurs.