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 loads heavily on the terminal coils of motor winding, the insulation failure in the motor winding occures mostly on the terminal coils. Therefore, it is reasonable to reduce turns of terminal coils only and to increase dielectric strength of interturn insulation.
This paper states about the comparison on measured characteristics of normal induction motor and the induction motor with reduced turns of terminal coils and about the comparison on the results measured and calculated by equivalent circuit. The appropriate rate of reduced turns of terminal coils is about 20%.