Study Of Calibration Instrumentation Of CT On Site Based On Low Voltage Method

Most traditional calibration technology for Current Transformer(CT) is based on difference measurement ,because of the limitation of the theory,it is difficult for calibration for CT on site.In the paper a new calibration method called low voltage method is proposed.The new method gains the ratio and phase error of CT by measuring the inner parameters of CT. According to the technology of designing intelligent insrumentation,the new calibration insrument is based on DSP processor, adopts digital sampling and advanced sinal processing technology. It can fufill the goal of calibration for CT on site by only one instrument. Firstly the paper introduces the new method of low voltage in detail, and then proposes two formula of the CT ratio and phase error. Because how to improve the measurement accuracy of CT parameters is the key of low voltage method, the paper in detail introduces the electronic parameters measurement circuit, furthermore,the needed digital sinal source ,CT ratio measurement circuit ,the way of digital sampling ang sinal processing are emphasized in the paper. In the measurement system TMS320F206 DSP processor is introduced to fulfill the calibration goal. Compared with other traditional calibration instrument,the new system can provide great benefit for calibrating CT on site, Because of its high automation ,fast measurement and its intelligent interface.