Rotating machine end turn grading during PWM transitions

The semiconductive armor tape (CAT) which covers a form wound stator bar within the slot extends beyond the slot in the end turn region to provide for connection to the nonlinear end turn stress grading (SG). At power frequency, the CAT acts as a conductor, but during PWM waveform transitions, substantial potential can drop across the CAT between the slot edge and the SG which can reduce the dissipation at the CAT-SG interface. We develop analytical approximations for grading during PWM transitions.