A sustained increase in temperature can reduce the life of a transformer by what percentage?

A sustained increase in temperature can reduce the life of a transformer by what percentage?

• A. 20%
• B. 35%
• C. 65%
• D. 50%

Answer: (D)

Temperature accelerates insulation aging in transformers. The insulation aging rate increases with temperature, and a commonly used rule of thumb is that for every 10°C rise above the design or ambient temperature, the insulation life is roughly halved. So a sustained temperature increase around 10°C reduces the transformer's life by about 50%. This is the best match among typical options. (For larger rises, the life would decrease even more—for example, a 20°C rise would leave only about 25% of the original life.)

Temperature accelerates insulation aging in transformers. The insulation aging rate increases with temperature, and a commonly used rule of thumb is that for every 10°C rise above the design or ambient temperature, the insulation life is roughly halved. So a sustained temperature increase around 10°C reduces the transformer's life by about 50%. This is the best match among typical options. (For larger rises, the life would decrease even more—for example, a 20°C rise would leave only about 25% of the original life.)