What is the use of magnetization curve of DC shunt generator?

The armature voltage is a critical parameter in the determination of

performance characteristics for the DC machine. The armature voltage has

been shown to be proportional to the magnetic flux density per pole and the

armature speed. Thus, the armature voltage will also exhibit nonlinear

behavior when saturation occurs. The analysis of DC machine performance

typically requires that the characteristics of the armature voltage saturation

be known. This information is typically provided in a plot of the armature

voltage vs. field current (magnetization curve) for a given operating speed