The current must be larger to produce the same active power. In this way kVA becomes larger because of this larger current. Starting from an ideal sine wave with current in phase with the voltage, as the phase angle increases, the current waveform occurs later and increases to a higher current. The RMS current increase produces a higher apparent power. With linear loads, both the Displacement Power Factor and Total Power Factor change at the same rate as the phase angle changes.
Apparent power can also be larger than active power when non-linear loads are present.
These loads produce harmonic currents which circulate back through the distribution system, and the secondary of the distribution transformer. Harmonic current adds to the RMS value of the fundamental current supplied to the load, but does not produce any significant power. Using the definition for total power factor, the kW is essentially that of the fundamental only, while the kVA is made larger because of the higher RMS current. Total Power Factor also includes the effects of any phase difference between the fundamental voltage and current. In many cases, when the distribution system is serving only single phase receptacle loads, the phase difference at the fundamental is minimal.