Traceable technique to calibrate current coils for calibration of the power clamp meters in AC current range up to 1000Â A

Power clamp meters are designed to check electricity meters, instrument transformers and installations on site. A measurement technique which is used to calibrate current coils for calibration of power clamp meters in AC current range from 5 to 1000 A has been developed. This technique allows one to measure two parameters of current coils that are needed for calibration of power clamp meters, they are the amplitude coil effect and the proposed phase coil effect. This is the first study of phase coil effect. There is presented the calibration procedure and an example solution of a fully automatic calibration system which employs the three phase Power/Energy Calibrator from Poland, which is traceable to the national standards. Calibration uncertainty of current coils, with reference to a power calibrator and measurement results, is discussed. The best expanded uncertainty (k = 2) of this technique equals 0.03% for amplitude coil effect and it equals 0.14° for phase coil effect. The expanded uncertainty for phase coil effect equal 0.14° gives expanded uncertainty for active power equal 0.42% at PF = 0.5 for calibration of power clamp meters. The result is that the power clamp meters specified accuracy (0.40%) has almost the same value as the power error due to the influence of phase coil effect (0.42%).