| Abstract | Results obtained by the National Research Council in a comparison of instrument transformer calibraitons with the Physikalisch-Technische Bundesanstalt of Germany and the National Bureau of Standards of the United States are presented, along with corresponding results obtained by the other two laboratories. Calibrations were carried out at a frequency of 50 cycles per second by all three laboratories. Additional calibrations were made at 60 cycles per second by the National Bureau of Standards and the National Research Council. Agreement between the laboratories, for the most part, appears to be of the order of one part in ten thousand. Somewhat larger deviations are present, however, in the calibration of potential transformers in the 100 to 300 kilovolt range at 60 cycles per second. Sources of error in the NRC equipment, and the corrections required for them, are also discussed. |
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