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10 kV high voltage electric energy meter is manufactured using new full-fiber optical current transformer, model selection process scheme is proposed at all aspects, all-fiber optical current transformer is improved in combination with the existing problems found in production, and finished-products are manufactured and tested for verification by improving the epoxy casting process. Keywords—all-fiber optical current transformer; high voltage electric energy meter; casting I. BACKGROUND OVERVIEW Currently, the power distribution network measures the electric energy through 10kV high voltage power metering box or electric energy metering cubicle, which means the high voltage power is measured by the access of standard low voltage (100V or 100/ 3 V) transformed from large voltage of high voltage and standard low voltage small current (5A or 1A) transformed from large current of high voltage through several high voltage electromagnetic current and voltage transformers to the electric energy meter,with its principle showm in Figure І. FIGURE I. MEASURING PRINCIPLE OF TRADITIONAL HIGH VOLTAGE ELECTRIC ENERGY However, there are many disadvantages in traditional electromagnetic transformer, such as frequent accidents, high energy consumption, high consumable material, poor error characteristic curve which cannot be exclusively determined, inconvenient management, difficulty in electricity larceny prevention. A new generation of full-fiber optical current transformer based on Faraday magneto optic effect is produced, which is mostly featured by its special sensing fiber at high voltage end, without the need of any other functional components to ensure no high voltage breakdown occurs, thus greatly improving the reliability of such transformer. It is gradually used to various high voltage and extra high voltage power grids. With the development of electronic, digital and communication technology, the full-fiber optical current transformer can be used to the 10 kV power grid reduced from the original power grid of above 110 kV due to its increasingly growing accuracy, even 0.2 s. For example, the full-fiber optical current transformer researched and developed by Shanghai Kangkuo Optical Communication Technology Co., Ltd., with voltage class of 10 kV-1200 kV, current measuring range of 25 mA-7500 A, measurement accuracy (IEC) of 0.2 S, protection accuracy (IEC) of 5P30, which completely satisfies the operating requirements of 10kV high voltage electric energy meter. As shown in FigureII, its principle is that the light from light source is polarized by polarizer via coupler, is divided into two beams with polarization direction mutually perpendicular after the phase modulation via modulator and gets into the sensing optical fibre via transmission optical fibre and is superposed coherently at photoelectric detector at end of sensing optical fibre. When there is no current in primary conductor, the relative propagation speed of the two beams of light is equal, which means there is no phase difference when they are superposed coherently at the detector; when it is energized, the propagation speed of the two beams of light changes under the action of magnetic field around the live conductor to cause phase difference, thus making the light intensity at the detector change accordingly. The current of primary conductor can be measured by measuring the light intensity. The casting process of the 10kV high voltage electric energy meter based on the full-fiber optical current transformer is explored and analyzed in this document. International Conference on Electrical, Electronics and Mechatronics (ICEEM 2015) © 2015. The authors Published by Atlantis Press 22 II. CASTING PROCESS OF EPOXY RESIN The epoxy resin is featured by the excellent electrical insulation property, high mechanical strength, heat resistance and resistance to chemical attack, good curing shrinkage rate and coefficient of linear expansion, good dimensional stability and manufacturability. Since the 1980 s, it has been used for the transformer, instrument transformer, insulator and other electrical products as main insulating materials, with its voltage rising from 10 kV and below to 35 kV. Its main processing method is casting, which means pouring the epoxy resin formula materials to the assembled work-piece mold and demold to get the finished product after the curing reaction. Such process is of integral dry insulation type, the dominant insulation method to realize the miniaturization, lightweight and low noise of electrical product and has experienced the process of development of normal pressure casting, partial vacuum casting, full vacuum casting and automatic pressure gelation (APG). We adopt the popular full vacuum casting process and summarize an effective process and get good application result in the sensing high voltage electric energy meter, with the advantages that the preparation, mixing and casting are under vacuum state to minimize the bubbles in the casted products, improve the product electrical insulation and mechanical property, improve the product yield and reduce the product cost and labor intensity. Its process is shown in Figure III: FIGURE II. PRINCIPAL BLOCK DIAGRAM OF FULL-FIBER OPTICAL CURRENT TRANSFORMER FIGURE III. FULL-VACUUM CASTING PROCESS We consider that as long as the full-fiber optical current transformer is reasonably designed, with high quality devices, it can satisfy the requirements for test and use after the epoxy casting. Digital output

Epoxy Casting Process and Complete Set Test for New 10 kV High Voltage Electric Energy Meter Based on All-fiber Optical Current Transformer