| Having been in development for nearly 30 years, electronic currenttransformers (ECTs) have been introduced into the market by a few famouscompanies abroad; some ECTs have been in reliable operation for years. Butdomestic ECT prototypes still have problems such as accuracy requirementand reliability over a long period. The thesis studies the accuracy andreliability for the prototype of an active ECT in depth. In the first chapter, the thesis gives a brief introduction to principle andresearch situation of a variety of ECTs; the definition of accuracy andreliability is also given in this chapter. In the second chapter, the thesis puts forward a calibrator to judge theaccuracy class of ECT. Among various methods used to calibrate ECT, thethesis adopts direct-acquisition method to develop a calibrator integrated withthe technique of virtual instrument. In this chapter, signal conditioning circuitand characteristic algorithm are stressed. Verified by Metrology Academy ofChina, the ratio error of the calibrator is in 0.05% and phase error in 4′. Thecoming forth of the calibrator gives an appropriate means for the researchwork of class 0.5 ECT. In the third chapter, the thesis brings forward test courses of class 0.5prototype in detail. A reasonable interpretation is also deduced for the testresults. From Electromagnetism Compatibility (EMC) tests and VoltageWithstand tests, the effect of EMC and insulation on reliability can be deduced.From the accuracy tests, the influence of primary current, environmenttemperature and vibration on accuracy can be concluded. Compared the resultsof laboratory tests and that of field trial, factors functioning on accuracy andreliability are then qualitative analyzed. In the fourth chapter, the thesis introduces the components of class 0.5 - II -prototype. After summarizing the factors and problems concerned accuracyand reliability, the scheme of class 0.2 prototype is given. The problemsoccurred in class 0.5 prototype are theoretically solved in the scheme.
|
PDF Full Text Request