Effect of inter-turn faults in modifying Line-end Coil Voltage Waveforms pertaining to low voltage Random Wound Induction Motors

摘要

Sinusoidal pulse width modulated pulses are used in adjustable speed drives for better efficiency. These pulses have high frequency components that propagate both along the coil and also in a traverse direction by capacitive coupling. End effect is a highly non-linear voltage distribution causing stress on inter-turn insulation. Such a stress tends to lower the insulation integrity in the motor. The mismatch between cables surge impedance and motor surge impedance causes a multiple reflection at the line-end coil and cable junction. Study have been made by computer simulation and verified by experiments. The patterns of disturbance in line-end coil voltage waveforms prove the presence of impending inter-turn faults.