In three-phase power, what is the percent increase in power capability for a 50% increase in conductors?

In three-phase power, what is the percent increase in power capability for a 50% increase in conductors?

• A. 50%
• B. 100%
• C. 25%
• D. 73%

Answer: (D)

In a balanced three-phase system, the total power is P = √3 V_L I_L. When you increase the number of conductors by 50%, the three-phase arrangement allows the current-carrying capacity to scale in a way that the overall power capability becomes a factor of √3 larger than before. Translating that into percent, the increase is (√3 − 1) × 100% ≈ 73%. So, a 50% increase in conductors results in about a 73% increase in power capability. The other options correspond to linear or smaller scaling that don’t match the √3 factor inherent in three-phase power.

In a balanced three-phase system, the total power is P = √3 V_L I_L. When you increase the number of conductors by 50%, the three-phase arrangement allows the current-carrying capacity to scale in a way that the overall power capability becomes a factor of √3 larger than before. Translating that into percent, the increase is (√3 − 1) × 100% ≈ 73%.

So, a 50% increase in conductors results in about a 73% increase in power capability. The other options correspond to linear or smaller scaling that don’t match the √3 factor inherent in three-phase power.