An Estimation Method of Starting Performance of Squirrel-Cage Induction Motor using the Two-Reaction Theory

Abstract

It is possible to estimate the starting performance of a squirrel-cage induction motor by the actual loading method, circle diagram method, equivalent circle method, and so on.
However, since these methods employ a commercial three-phase power supply, the testing equipment used becomes large-scaled with the increase in capacity of the tested equipment.
The set tester used at the testing factory can be sized down if the starting performance can be estimated by standstill tests using small-capacity devices.
In this paper we propose a new method which can estimate the starting performance by standstill tests using a small-capacity D. C. power supply. In this method, a D. C. current is first made to flow through the armature winding (two terminals with the third one open) of an induction motor.
Then the current decay, caused by short-circuiting between the two phases, is recorded.
The operational impedance on the induction motor per phase is determined by Fourier transformation of the current decay.
The starting performance is obtained using the two-reaction theory.
This paper shows that this method is clearly useful as an estimation method for the startig performance.