AN IMPROVED 3-PHASE DIGITAL RECORDER SYSTEM FOR CALIBRATING POWER INSTRUMENTATION

The paper describes an improved digital recorder system which is being used to provide reference values of voltage, current, active, reactiv e and apparent powers and harmonic quantities for three-phase sinusoid al and nonsinusoidal calibrations. The system has been designed to be used in the laboratory at the National Research Council of Canada (NRC ) or transported on-site for tests in electrical utility facilities. T est results have shown that for sinusoidal waveforms, the accuracy of the voltage and current measurements of the digital recorder is better than 25 mu V/V or mu A/A of full scale and better than 50 mu W/W of f ull scale for active and apparent power measurements, The accuracy of the system for measurements under the seven distorted waveforms condit ions most commonly used at NRC [1] is better than 50 mu V/V or mu A/A of full scale for voltage and current measurements and better than 100 mu W/W or mu VA/VA of full scale for active and apparent power measur ements.