Impact of transformer impedance on squirrel-cage induction motors behavior during symmetrical and unsymmetrical voltage sags

Impact of electric transformer impedance on squirrel-cage induction motor (SCIM) behavior, namely torque peaks and loss of speed, during symmetrical and unsymmetrical voltage sags is qualitatively analyzed on three-phase SCIM in this paper. These effects depend on several variables like sag type, duration and depth. The presence of transformer impedance always results in torque peaks higher than when the transformer impedance is not considered and predicts that voltage sags can produce motor instability. The simulations carried out allow an understanding of the performance of SCIM when the interconnection transformer is considered.