Equivalent Circuit and Characteristics of Induction Motor with reduced turns of Terminal Coils

Abstract

The use of PWM-inverter with high switching characteristics for the adjustable speed drive system causes the overvoltage with steep-fronted waveform on the motor terminals. As this steep-fronted transient voltage in inverter drive burdens heavily on the terminal coils of motor winding, the insulation failure in the motor winding occures mostly on the terminal coils. On this reasons, it is reasonable that the dielectric strength of interturn insulation is increased only on the terminal coils by reducing turns of the terminal coils.
This paper states about the equivalent circuit taking the space harmonic into account and the starting and operating characteristics of the induction motor with reduced turns of the terminal coils.