Latest Technology in Current Measurement
Over the past 15 years, optical current sensors have received significant attention by a number or search groups around the world as next generation high voltage measurement devises, with a view to replacing iron-core current transformers in the electric power industry.
Optical current sensors bring the significant advantages that they are non-conductive and lightweight, which can allow for much simpler insulation and mounting the designs. In addition, optical sensors do not exhibit hysteresis and provide a much larger dynamic range and frequency response than iron-core CTâ€™s. A common theme of many of the optical current sensors is that they work on the principle of the Faraday effect.
Current measurement plays an important role in protection and control of electric power systems. With the development of the conventional CT, the accuracy of the CT is up to 0.2% in the steady state power system. However many disadvantages of the conventional CT appear with the short circuit capacities of electric power systems getting larger and the voltage levels going higher for example, saturation under fault current conditions, ferroresonance effects, potential for catastrophic failure etc. Today there is number of interest in using optical current transformer (OCT) to measure the electric current by means of Faraday effect. The benefits of an OCT are the inverse of the conventional CTâ€™s problems. That is, no saturation under fault current conditions, with out iron core and there fore no ferroresonance effects, with out oil and there fore cannot explode, light weight, small size, etc.
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