1992 Volume 112 Issue 1 Pages 73-80
It is almost impossible to measure the starting performance of middle and large synchronous motors in a factory, because it needs a large capacity of equipments to test their performance.
A new method is required to predict their performance by simple tests using a small capacity. This will make the motor's design and accessories more rationalized.
Authors propose a new method which predicts the frequency response by using values of DC decay test in the armature winding at standstill.
The key points of this method are summarized as follows:
(1) DC voltage is applied to the armature winding (two terminals with the third one open) of a synchronous motor through a resistance. When two terminals are closed, the winding is shortcircuited and the current in the armature winding decays. The whole process of current decay is recorded. The impedance on motor terminals per phase are decided by Fourier transformation of the current decay.
(2) This new method is quite useful. It is possible to predict easily and exactly a low frequency response below one Hz.
The starting performance of a synchronous motor is predicted and agrees with actual data.