Which condition indicates that a power line is operating at optimal load?

A power line operating at optimal load is indicated by a power factor near 1. The power factor is a measure of how effectively electrical power is being converted into useful work output and is expressed as the ratio of real power (used for actual work) to apparent power (the total power in the circuit). A power factor close to 1 signifies that the majority of the energy supplied is being effectively used, with minimal losses to reactive power, which is associated with the energy that oscillates between the source and the load but does not perform useful work.

When the power factor is near 1, it means that voltage and current are in phase and that the system is efficient. This optimal loading reduces strain on both the electrical infrastructure and generation sources while minimizing waste. In contrast, options like voltage fluctuations indicate instability in the system, high reactive power demand points towards inefficiency and higher losses, and excess generation capacity may signify that the system is not being fully utilized. All these conditions detract from the optimal performance of a power line.