A precision current comparator for calibration of current transformers

The current comparator is a highly precise and stable a. c. current ratio measuring device. Essentially it is a 3-winding type current transformer, but with incorporation of additional windings its performance is greatly improved. The paper deals with the fabrication of a precise current comparator having ratios of 1/1 to 20/1 with a standard 5-Amp secondary winding. A 100/1 ratio has also been provided employing a bar primary. By suitable design it can be made more accurate than the best types of current transformers available. This inherent accuracy makes a current comparator an ideal device for calibration of current transformers in the laboratory or in industry. Several test results on such current transformers have been given.