الفهرس 
Cover EnglishOnly 14 pages are availabe for public view
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Abstract
Voltage transformers (VT’s) are one of the most common conventional methods of measuring high voltage. However they suffer from some major problems such as the interference resulting from additional load, limited bandwidth and relatively bulk size and high cost due to the requirement of many voltage dividers. Recently, optical techniques of measuring electric power, either current or voltage, gained a great interest in virtue of electrical isolation, elimination of the electromagnetic interference, high precision and accuracy, wide bandwidth from DC to GHz, compact size and low cost. Based on the linear electro-optic effect, “Pockels effect”, linearly polarized light propagating in the Pockels crystal (BGO) parallel to the electric field will experience phase retardation between its components in the slow and fast axis. The phase retardation is due to the difference in the velocity of propagation of the light and is related to different refractive indices of the axes which are proportional to the applied electric field. The value of the phase retardation indicates the value of the voltage difference through the crystal. The sensitivity of the optical Pockels systems in longitudinal configurations was limited by the value of the maximum detectable voltage (Vπ). In order to overcome the limitation of previous systems a modified system is designed, constructed and tested based on the transverse Pockels effect in which the electric field direction is perpendicular to the direction of light propagation. In our design the total applied high voltage is the integral path of the electric field through the crystal and the surrounding medium. It benefits of the ability of altering the value of the electric field inside the crystal for the same applied high voltage by varying the separation between the two electrodes; (high potential and ground electrode). In this case for the same value of the total applied high voltage more than one phase retardation can be measured proportional to the electric field inside the crystal so that theoretically high voltages more than Vπ and up to several hundred values can be measured. The system based on longitudinal configuration is carried out numerically and implemented experimentally measure high voltages directly, without the use of voltage dividers and without expensive insulation, DC (up to 18 kV) and AC (up to 12 kVrms, 50 Hz). The experimental and calculated values were in very close agreement, with deviation of small percentage 3% for DC readings and 2% in AC readings. On the other hand, the system in transversal configuration is studied as well and simulation by FEM for the system is introduced to study different design parameters in order to optimize the design of the system and to find the relation between the electric field intensity within the crystal and the value of the total applied voltage depending on shape of the crystal, the permittivity of the material and the distance between the electrodes. AC high voltages were measured by the system in transversal configuration with a relative error of 3%. Due to the ambiguity of the measurement for values higher than Vπ/2, a numerical solution is proposed, depending on the variation of electrodes separation. Thus the ambiguity is removed and the measurement range is increased.