The generalized equivalent circuits, which develop the known theorems, are formulated. It appears that the load straight line at various values of a changeable element (resistor) of an active twopole passes into a bunch of these lines. The bunch centre coordinates do not depend on this changeable element. It is proposed to use as the parameters of the generalized equivalent generator such a load current and voltage, which proved the current across this element equal to zero. The application of projective coordinates instead of resistance values allows obtaining suitable formulas of the recalculation of the load current, to define the scales for the load and variable element.