The Equivalent Generator Theorem
V.D. Landon · Proceedings of the IRE · 1930
It is proved that any electrical network with two output terminals may be replaced by a generator and a series impedance without changing the current in an externally connected load. The voltage of the generator is the no-load voltage of the output terminals. The value of the series impedance is the impedance of the unloaded network looking into the output terminals. The use of the theorem is illustrated, and it is pointed out that it is valid for transient as well as steady state conditions.