Rotating electric machine time constants at low speeds

THE use of the concept of time constants in the analysis of a-c rotating electric machine transients is well known.¹ It is also well known that the short-circuit time constants of machines running at normal speed are not at all like those of the same machines at rest. The purposes of this paper are to show the continuous nature of the variation of the machine characteristics in the range of speed from zero to rated speed, and to determine the limits of applicability of the full-speed and standstill values and the behavior at low speed.