A practical on-line electro-optic measurement equipment for the measurement of electric field and space charge distribution in an electrode geometry with nonuniform electric field distribution

Abstract

Summary form only given. Due to the effect of space charge, the electric field distributions cannot be calculated from knowledge of system geometries and material dielectric properties alone using Laplace's equation, as the system is then described by Poisson's equation. To optimize the electrical insulation design, it is necessary to on-line obtain the electric field distribution between the electrical electrodes. The Kerr electro-optic technique has the advantage that the devices create less disturbances in the field distribution itself. In the past, most Kerr electro-optic measurements have been limited to cases where the electric field direction and magnitude are constants along the light path for the electric field measurement results are the integration effects along the direction of light propagation. In many reality circumstances, the electrode structures which generate nonuniform electric field are common, so the direction of the electric field vector is no longer constant and may be variable along the light propagation direction. Some transformations which are being used in image reconstructions can be used in these cases to obtain the electric field distribution for a specific electrode structure. But, by using this method, many data should be obtained in the space between the electrodes, and this is usually realized through the movement of optical measurement system using some mechanical devices, and these mechanical devices may be the principle error sources for the rigid requirements of the optical measurement. Beside, after many data from different space points obtained, the electric field reconstruction can only be implemented in a PC off-line. The entire measuring processes are tiredness and complicated. In this paper, we use an electro-optical measurement matrix to measure the electric field distribution of the nonuniform electrode structure without any mechanical devices. The output of all PINs in the electro-optical measurement matrix are connected to a precise data acquisition board, together with the high speed embedded MCU to realize the transformation of the measuring results using ABEL transforms in real time, the electric field and space charge distribution are on-line obtained. The measuring results are given for needle-plane electrodes immersed in propylene carbonate.