Method of Limiting Shaft Voltages in AC Electric Machines

Effect of PWM Inverters on AC Motor Bearing Currents and Shaft Voltages

wavefronts especially increase the magnitude of the above electrical problems, leading to motor bearing material erosion and early mechanical failure. Previous literature suggests that shaft voltage-bearing current problems under 60 Hz sinewave operation are predominantly electromagnetically induced. It is proposed that under PWM operation these same problems are now predominantly an electrosta...

Measurement of Ac Voltages with Digital Voltmeters

A principle of using high-resolution digital voltmeters (DVs) HewlettPackard 3458A for the measurement of AC voltages in DCV range is described. The method of approximate synchronous sampling is used, having only one sample per cycle of a working frequency close to 16 Hz, when the mean value of one-third cycle is measured. The beginning of integration is shifted for the same interval for every ...

Strongly nonlinear dynamics of electrolytes in large ac voltages.

We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes, ignoring any transverse instability or fluid flow. We analyze the resulting one-dimensional prob...

Precision Measurement of Ac Voltages in the Millivolt Ranges

− The paper describes the systems, the standards and the procedures developed at IEN for the precise measurement of ac voltages in the millivolt ranges. Two different methods based on resistive dividers and wideband transformers have been developed and are applied for the measurements of respectively the ac-dc transfer difference and the ac voltages down to 1 mV.

DESIGN OF ELECTRIC MACHINES: Axial Flux Machines