The Research Of Data Acquisition And Communication System Of Active Electronic Current Transformer

Active electronic current transformer offers a number of advantages such as excellent anti-electromagnetic interference ability , wide dynamic range , simple insulation structure, small and light , ease to interface to computer. Its sensor is not easily influenced by external environmental factors compared with optical current transformer, so it has better developing prospects.Firstly, this paper introduced the general structure of three kinds of electronic current transformers described in standard IEC60044-8, then analyzed several practical methods on the signal modulation - demodulation and proposed the design principles of signal modulation - demodulation adopt by the electrical current transducer.For the output signal of Air Core Coil is proportional to the differentiation of measured signal, the paper designed the system modulation - demodulation schemes which high voltage side is based on energy meter IC ADE7759 and the low voltage side is based on TMS320F2812 . The energy meter IC ADE7759 has digital integrator and 24 bit A/D Converter inside. This scheme can not only effectively conquer the existing problems such as time-drift and temperature-drift in analog integrator but also could have the sampling resolution up to 0.477μV . The test result indicates that this setting scheme is practical and effective , and can satisfy the requirements of IEC60044-8 0.2 class.The large power consumption of high voltage side is a bottle - neck of active electronic current transformer which powered by laser energy from the low voltage side. It not only requires the laser has large optic-power output,but also influence its lifetime , and reduce the Reliability of the System accordingly. For this reason, another scheme has been make out. It adhibits low-power consumption MCU MSP430F149 as the host controller chip of data acquisition system in high voltage side , uses the simplified low-power electrical circuit and appropriately encoding methods as the assistant for data acquisition and transmission. The test result shows that the power consumption of high voltage side circuit is lower than 46mW, its linearity is less than 1%, and the step response time of the whole system is about 460μS. It provides another feasible technical solution for active electronic current transformer.