The pressure in a transformer can build up and _____________.

• A. Blow off the lid
• B. Melt the core
• C. Increase efficiency
• D. Reduce heat

Answer: (A)

When a transformer operates, heat plus gas formation in the insulating oil can raise the internal pressure. To prevent dangerous pressure levels from causing seals to fail or an explosion, the design includes vents that release the gas. So, when pressure builds up, it will blow off the lid to relieve that pressure. The other ideas don’t fit what happens with pressure: melting the core isn’t a typical relief mechanism, increasing efficiency isn’t a result of pressure buildup, and reducing heat doesn’t describe the actual relief process.