This paper presents a method for maximizing the operation area of the capacity curve of a synchronous machine. The technique is set in P-Q plan in order to adjust more features of minimum excitation and practical stability limits of the capacity curve. Thus, the voltage limiter can be intended to the left of the capacity curve and so the machine may have an operating gain in this region. The new setting is done primarily on the generator capacity curve, plan P-Q, and subsequently analyzed in the R-X plan.