The efficiency of three-phase power transmission is primarily due to which factor?

The efficiency of three-phase power transmission is primarily attributed to the reduction in transmission losses. In three-phase systems, power is transmitted more effectively compared to single-phase systems because the power delivered at any given time is more constant. This constant power flow minimizes fluctuations and reduces the likelihood of energy being lost as heat in the conductors.

Additionally, three-phase systems can transmit more power over a given conductor size than single-phase systems, which means that for the same amount of power, the current flowing through the conductors is lower. This reduction in current results in lower I²R losses (where I is the current and R is the resistance of the conductor), further enhancing efficiency.

The other factors mentioned, such as lower physical dimensions, higher maintenance requirements, and increased operational complexities, do not directly relate to the efficiency of power transmission. While smaller dimensions may aid in some applications, they are not the primary reason for efficiency gains. Similarly, maintenance and operational complexities are more about the challenges of managing these systems rather than enhancements in efficiency. Thus, the primary factor leading to higher efficiency in three-phase power transmission is indeed the reduction in transmission losses.