Which type of power cannot be transmitted over long distances without considerable loss?

Which type of power cannot be transmitted over long distances without considerable loss?

• A. Alternating Current (AC) power
• B. Three-phase power
• C. Wireless power
• D. Direct Current (DC) power

Answer: (D)

The main idea is that transmission losses come from the current in the lines. Since line losses scale with the square of the current (I^2R), sending power with as high a voltage as possible and as low a current as possible minimizes losses. Alternating current makes this easy because transformers let you step up the voltage for long-distance transmission and then step it down near the load, keeping current low along the run. Three-phase power is still AC, so it shares that advantage and can be transmitted efficiently over long distances with the right infrastructure. Direct current, however, doesn’t have a straightforward way to raise and lower voltage along the route with common equipment, so keeping the current low over long distances is much harder, leading to greater losses. Although HVDC systems exist for very long or submarine links, the general principle in this context is that direct current power cannot be transmitted over long distances without considerable loss. Wireless power, by contrast, is not practical for bulk long-distance transmission due to significant inefficiencies.

The main idea is that transmission losses come from the current in the lines. Since line losses scale with the square of the current (I^2R), sending power with as high a voltage as possible and as low a current as possible minimizes losses. Alternating current makes this easy because transformers let you step up the voltage for long-distance transmission and then step it down near the load, keeping current low along the run. Three-phase power is still AC, so it shares that advantage and can be transmitted efficiently over long distances with the right infrastructure. Direct current, however, doesn’t have a straightforward way to raise and lower voltage along the route with common equipment, so keeping the current low over long distances is much harder, leading to greater losses. Although HVDC systems exist for very long or submarine links, the general principle in this context is that direct current power cannot be transmitted over long distances without considerable loss. Wireless power, by contrast, is not practical for bulk long-distance transmission due to significant inefficiencies.