what is V-Curve of synchronous motor ?

what is V-Curve of synchronous motor?

 Curves of armature current vs. field current (or excitation voltage to a different scale) are called V curves and for typical values of synchronous motor loads. The curves are related to the phasor diagram and illustrate the effect of the variation of field excitation on armature current and power factor for typical shaft loads. It can be easily noted from these curves that an increase in shaft loads require an increase in field excitation in order to maintain the power factor at unity

the graph plotted between field current and armature current is known as the V curve. since the shape of this curve is looks like v in shape so this curve is known as v curve.

Handwritten notes are below