Results of an International Comparison of Instrument Current Transformers up to 10 kA at 50 Hz Frequency

Traceability of the current ratio is crucial for the measurement of electrical energy in revenue metering. A comparison of the AC current ratio was therefore performed within EURAMET in the time period 2012 - 2016, using a precision CT as the traveling device. The Czech Metrology Institute (CMI) as coordinator processed the measurement results of the 15 European participating laboratories. The comparison of the results for transformer ratios of (4, 5, 6, 8, 10) kA/5 A at 15 VA burden and (4 and 10) kA/5 A ratios at 5 VA burden indicates good agreement between the participating laboratories. The main differences are found for phase displacement, at least in part due to instability of the traveling standard.