Date of Award

1989

Publication Type

Dissertation

Degree Name

Ph.D.

Department

Electrical and Computer Engineering

Supervisor

P.H. Alexander

Supervisor

R. Hackam

Rights

info:eu-repo/semantics/openAccess

Abstract

A Charge Simulation based Computer-Aided Design (CAD) Package which facilitates the development of a charge simulation model for high voltage (HV) systems consisting of a number of electrodes and one or two dielectric regions has been developed. The package calculates the potential and electric field distributions for practical systems. It avoids the necessity for creating individual programs for each system studied by allowing the geometry to be specified using a minimum of entered data. The application of the CAD package to several electrode systems which have analytical solutions is presented. Good agreement, generally within 0.5% was found between the fields produced by the Charge Simulation Method (CSM) and the analytical results. A study of the effect of several parameters controlling the charge simulation model is conducted to determine their optimum ranges. Recommendations for these values are made. It is found that for best simulation, discontinuities in alignment of the simulating charges should be avoided. The rod-plane gap configuration and a HV shielding system are modelled and results are compared with existing literature values. Some simulation quality measures which have not previously been published are given. The computation of fields in a sphere/slab arrangement is conducted and results are presented for a wide range of permittivity ratios and gap spacings. It is found that the maximum electric field strength occurs at the triple point for high dielectric constant unrecessed slabs, and away from the axis for low dielectric constant slabs. Two high. voltage systems which have not been analyzed before using the CSM are studied. One is a rotationally symmetrical triggering electrode configuration. The other is a 22 - shed - V - polymer insulator with a grading ring included to reduce the non-linearity of the voltage distribution. In the triggering electrode system it is found that both the main gap distance and the pilot gap distance affect the potential and the field distributions along the axial main gap line. The location of the maximum electric field changes with both gaps and always occurs on the hemispherical part of the triggering electrode, but not necessarily at the tip. Optimum values for the location and size of the grading ring are determined for the polymer insulator. TI1e simulations of additional complicated three-dimensional field problems with and without axial symmetry using the CSM are presented. A tilted rod-electrode versus ground plane and a hemispherical capped rod electrode versus a grounded plane with another offset hemispherically capped electrode embedded are modelled. A detailed examination of the field distribution for a triggering high voltage system without axial symmetry is also presented.

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