This diagram shows the inductance curve of a small mains line choke with laminated iron plate core. The manufacturer specifies the inductance value at 15 H at 30 mA. Typical application is passive power factor correction.
In that case again the typical inductance curve of iron based core materials can be seen. The initial inductance is much lower than the inductance at nominal current due to the low initial permeability. A small signal measurement yields in misleading and not reproducible results that are too low.
Sometimes it is helpful to display the inductance as a function of the voltage-time-integral ∫U(t)dt applied to the inductor. Both display modes are togglable at the Power Choke Tester DPG10.