International comparison of current transformer calibration systems up to 10 kA at 50 Hz frequency

Current transformers (CTs) are precision devices that scale high currents down to values that can be easily handled by measurement equipment. To support CT applications in revenue metering, a comparison on AC current transformer calibration systems was performed among 15 European national metrology institutes using a precision CT as the travelling device. The first comparison results for the transformation ratios (4, 5, 6, 8, 10) kA/5 A of the travelling CT at nominal burden of 5 VA and 15 VA indicate good agreement between the participating laboratories. The main differences are found for phase displacement, at least partly caused by the instability of the traveling standard.