Fiber optic current sensor calibration

Abstract

Fiber optic current sensors have been touted for their potential ability to measure currents with accuracy better than 0.1% over a dynamic range extending from literally milliamps to hundreds of kiloamps. Such claims have a good theoretical basis but it is quite difficult to verify such claims, especially at the two extremes of this range. At the lower end of the current range, white noise in the output compares to, or exceeds the signal level and thus interferes with the measurement process. At the upper end of the range, equipment limitations come into play. In our laboratory we have undertaken a careful study of calibration techniques appropriate to manufacture fiber optic current sensors in the range from 1 to 3600 amps. The main results of our study are reported in this paper. Voltage techniques applied yielded errors of about 0.015% in the range from 1 to 100 amps, and 0.054% in the range from 100 to 3600 amps. The current techniques applied can yield 0.001% errors in the range from 1 to 100 amps (though practically, this would be degraded to save time) and 0.054% in the range from 100 to 3600 amps.