Which factor primarily contributes to asymmetrical current behavior?

The factor that primarily contributes to asymmetrical current behavior is transformers and reactors. This occurs because these devices can introduce non-linear characteristics into the electrical system. For instance, when transformers operate under different loads or when there are variations in supply voltage, they can lead to imbalances in current flow, which is a principal cause of asymmetrical current.

Transformers can create different phase shifts and magnitudes of currents because of their winding configurations and the differences in their electrical characteristics. Additionally, reactors can impact the reactance in the circuit, including inductive and capacitive elements, further influencing the asymmetry in the current being drawn from the source. Thus, the behavior of these components plays a significant role in creating imbalances in the electrical system.

While the other factors like equipment age, cable length, and weather conditions can influence overall performance or efficiency, they do not directly cause asymmetrical currents to the same extent as transformers and reactors, which are specifically designed to influence voltage and current distributions in power systems.