Transient torques in synchronous machines

THIS paper determines first the electrical torques due to short circuit as considered from 2 points of view — a machine without losses, and then including losses. The further calculation of the mechanical torques, i. e., shaft and coupling torques, torque reactions in spring mounted machines, etc., shows that the loss torques can result in as serious mechanical stresses as the alternating torque components, though the latter be higher. This is due to the effect of the “transmission factor” discussed in the paper. The calculation of stator stresses shows them to be low, even under a short-circuit torque which is considered to act undiminished because of stator frame rigidity.