Experimental research on measuring and testing techniques of electronic current transformer

The research of electronic current transformers (ECTs) has stepped into the practical stage, but at the time being there is a lack of integrated testing method for ECTs. According to the standard of IEC 60044-8, the output characteristics of ECTs are systematically analyzed, and the corresponding testing theories and methods are discussed. From the point of view of metrology, the reference standard is constructed through an unbroken chain of comparisons all having stated uncertainties. The reference standard satisfies with the requirements to calibrate the current transformers having steady state accuracy 0.2%. Based on virtual instrument techniques, a testing system for ECT is constructed in laboratory. By means of data acquisition devices, the valuable data are inputted into computer. And then the functions of analyzing, processing, saving and controlling are accomplished based on LabVIEW platform. This system can be used not only to test lower voltage analog signals precisely, but also to calibrate the digital signals directly by simultaneous sampling techniques. The designed prototype of ECT is tested by using this testing system, The testing results demonstrate that the prototype can reflect the measured current accurately, and the steady state measurement accuracy exceeds the IEC standard 0.2% within the temperature range from -40degreesC to +60degreesC.