150 MW is flowing into the high side of a 200 MVA transformer. If the transformer windings have a 2 to 1 ratio, what MW value is flowing out of the low side winding of the transformer?

• A. 250 MW
• B. 200 MW
• C. 75 MW
• D. 150 MW

Answer: (D)

The fundamental principle to consider with transformers is that they ideally transfer power without losses. In this scenario, 150 MW is entering the high side of the transformer. The transformer's turns ratio of 2 to 1 indicates that the secondary side or low side will have half of the voltage compared to the primary side while maintaining the same power level.

Since power is conserved in an ideal transformer (ignoring losses), the power flowing out of the low side must remain equal to the power flowing into the high side as long as we remain within the operational limits of the transformer. Therefore, regardless of the voltage transformation, the MW value at the low side will also be 150 MW.

This understanding aligns with the principles of transformer operation, which states that the input power (in MW) equals the output power under ideal conditions, affirming that the value flowing out of the low side winding of the transformer is indeed 150 MW.