Computer aided techniques for estimation and reduction of electromagnetic measurement devices uncertainties

At non-linear electromagnetic measurement systems, the finite element method is the most convenient tool for the system analysis and measurement uncertainties budget estimation. Two non-linear devices will be analyzed by finite element method: electrical steel sheet testing device-Epstein frame and combined current-voltage instrument transformer. The Epstein frame must comply with the standard IEC 60404-2:1996+A1:2008, and the combined instrument transformer with the IEC 60044-3: 2002. The Epstein frame forms an unloaded transformer and the analytical transformer theory introduces some approximations. The main approximation is introduced by the standard IEC 60404-2 (through the presumption of constant, invariant to the specimen grade effective magnetic path length). The finite element method results will enable an Epstein frame and combined current-voltage instrument transformer prototype design (by using a computer program based on genetic algorithm with minimal uncertainty budget as goal function) with reduced measurement uncertainty, which will be experimentally verified in the Metrological Laboratory for Electromagnetic Quantities at the Faculty of Electrical Engineering and Information Technologies-Skopje

Calibration of a Virtual Instrument for Power Quality Monitoring

Abstract. The paper describes a virtual instrument for power quality monitoring based on NI LabVIEW™ platform and simultaneous measurements of electrical voltages and currents. The virtual power quality analyzer is realized by using National Instruments 9225 and 9227 modules for voltage and current measurements, respectively, NI cDAQ 9174, 4 slot USB chassis and a PC. The created virtual instrument measures power quality characteristics: power frequency, voltage variations, magnitude of rapid voltage changes, flicker severity, voltage unbalance, total harmonic distortion, as well as the elements of voltage dips, short interruptions, and long interruptions defined in the standard EN 50160 for voltage characteristics of supplied electricity. The measurement is according to the general guide on harmonics and interharmonics measurements IEC 61000-4-7. The calibration and verification of the power quality analyzer is a complex task and it is performed by using the laboratory calibrator FLUKE 5500A. The results of calibration and verification of the developed virtual instrument, as well as the results of power quality measurements near different lightning technologies are presented