Where should you expect to find the transformer pressure-relief valve physically located?

• A. At the bottom tank
• B. Above the oil level
• C. Inside the transformer core
• D. On the external cabinet

Answer: (B)

The key idea is that the pressure-relief device must vent the gas space inside the transformer tank, not the liquid oil. If the valve is placed above the oil level, it sits in the gas space and can relieve pressure safely without dealing with oil. This dry location ensures gas, not oil, is expelled when overpressure occurs, reducing the risk of oil spray or liquid leakage and allowing reliable operation and inspection. Placing it at the bottom, inside the core, or on an external cabinet would either put it in oil, in the magnetic core area, or outside the tank where it can’t properly sense and vent the internal gas pressure. So you should expect the valve to be mounted on or near the top of the tank, in a space above the oil level.