My experience with generators tell me that the impedance of the coil will work as a voltage drop source and today I understood it is the same as the leakage inductance of a transformer
Basically the effect is that a greater current at the load reduces the voltage at the secondary
The lower is the coupling the greater will be the leakage inductance... also resistance of the coils limits theirs coupling
Graphs Can be plot with the voltage as function of load and find the leakage
Transformers are normally better coupled than generators so in generators I noticed this effect before
https://en.m.wikipedia.org/wiki/Leakage_inductance
