Power quality

The overall management of power quality and its limits is the subject of specific Engineering Recommendations and Distribution Code. From a losses perspective, two aspects are most relevant:

Harmonic effects are distortions to an Alternate Current (AC) profile and can occur in transformer windings because the magnetising current is not perfectly sinusoidal.

Harmonics can develop from distorting loads usually associated with industrial processes, for example arc furnaces, or more widely from domestic customers equipment such home appliances, air conditioning units, fluorescent and LED lights, computers and other non-linear loads are connected to the network.

The United Kingdom electricity network operate on three phases with electricity transported along three conductors. The electricity network is designed to be balanced, meaning that the current flowing on each of the three phases has the same magnitude, with an offset of 120 degrees between phases.

The dynamic nature of electricity generation and consumption means that network power flows are not evenly distributed across all three phases, with higher currents in at least one phase and excess current flowing through the neutral conductor if present. Due to the quadratic dependence of losses with current, this load unbalance increases energy losses.