Time Evolution of the Potential Distribution in Earth Alkaline Titanates under de Voltage Stress

1988 ◽  
Vol 92 (12) ◽  
pp. 1516-1522 ◽  
Author(s):  
A. Raith ◽  
P. Reijnen ◽  
R. Waser
Keyword(s):  
Time Evolution ◽  
Potential Distribution ◽  
Voltage Stress

scholarly journals Method to Predict the Non-Uniform Potential Distribution in Random Electrical Machine Windings under Pulse Voltage Stress

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 358
Author(s):  
Alexander Hoffmann ◽  
Bernd Ponick
Keyword(s):  
Equivalent Circuit ◽  
Potential Distribution ◽  
Solution Process ◽  
Practical Method ◽  
Electrical Machine ◽  
Stator Core ◽  
Design Data ◽  
Potential Oscillations ◽  
Voltage Stress ◽  
The Time Domain

This article describes a practical method for predicting the distribution of electric potential inside an electrical machine’s winding based on design data. It broadens the understanding of winding impedance in terms of inter-winding behavior and allows to properly design an electrical machine’s insulation system during the development phase. The predictions are made based on an frequency-dependent equivalent circuit of the electrical machine which is validated by measurements in the time domain and the frequency domain. Element parameters for the equivalent circuit are derived from two-dimensional field simulations. The results demonstrate a non-uniform potential distribution and demonstrate that the potential difference between individual turns and between turns and the stator core exceeds the expected values. The findings also show a link between winding impedance and potential oscillations inside the winding. Additionally, the article provides an overview of the chronological progression of turn-based models and shows how asynchronous multiprocessing is used to accelerate the solution process of the equivalent circuit.

The effects of surface absorbed monolayer microdiffraction patterns

1988 ◽  
Vol 46 ◽  
pp. 680-681
Author(s):  
M. Pan ◽  
J.M. Cowley
Keyword(s):  
Surface Potential ◽  
Electron Probe ◽  
Potential Distribution ◽  
Crystal Surface ◽  
Normal Direction ◽  
Surface Image ◽  
Extended Surface ◽  
Gas Molecules ◽  
Surface Nature ◽  
Electron Microdiffraction

Electron microdiffraction patterns, obtained when a small electron probe with diameter of 10-15 Å is directed to run parallel to and outside a flat crystal surface, are sensitive to the surface nature of the crystals. Dynamical diffraction calculations have shown that most of the experimental observations for a flat (100) face of a MgO crystal, such as the streaking of the central spot in the surface normal direction and (100)-type forbidden reflections etc., could be explained satisfactorily by assuming a modified image potential field outside the crystal surface. However the origin of this extended surface potential remains uncertain. A theoretical analysis by Howie et al suggests that the surface image potential should have a form different from above-mentioned image potential and also be smaller by several orders of magnitude. Nevertheless the surface potential distribution may in practice be modified in various ways, such as by the adsorption of a monolayer of gas molecules.

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