The primary source of voltage unbalance that is less than 2% is caused by what type of load(s)?

Voltage unbalance in a three-phase system occurs when the voltages in the three phases are not equal. When the unbalance is less than 2%, single-phase loads are typically the primary contributors. Single-phase loads draw power from only one phase of the three-phase supply, leading to differences in voltage levels across the phases.

This imbalance occurs because the other two phases are still carrying load, affecting the overall voltage equilibrium. In systems where most loads are single-phase, particularly in residential or mixed-use settings, the cumulative effect of these loads can result in a small percentage of voltage unbalance.

In contrast, balanced three-phase loads, such as resistive three-phase loads, would not contribute to voltage unbalance. Capacitive loads can create other issues in power quality but would not primarily lead to unbalance. Therefore, single-phase loads are the main reason behind a voltage unbalance that remains below the 2% threshold.