When looking at a typical phasor diagram on a meter, it is assumed the current phasors are rotating counter clockwise, with the voltage phasors stationary at their pre-determined locations. For demonstration purposes, Figure 1 is a 4 wire wye configured system, with ABC rotation.  Phase A voltage, or Va, lays on the primary “x” axis at 0° phase shift.  Ia is laying on top of the voltage phasor at 0° as well, indicating unity power factor, or a power factor of 1.  Phase B and C voltages and current pairs are separated by 120 degrees.

When a phase shift between the voltage and current occurs, this is due to reactance on the load, typically in the form of inductance.  This creates a lagging power factor.  When something is referenced as leading or lagging, this is a means of relating the phase relationship of the current waveform to the voltage waveform, and is always with reference to what the current is doing.  ///

quadrants