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What does the 's' on the Power Meter Accuracy class 0.2s & 0.5s mean?

FA276243

01 March 2021

It refers to the accuracy of the meter. A 0.2s meter has a much higher accuracy as below.

Since Accuracy depends on the load of the system, IEC/AS have developed different standards to define accuracy under different load conditions, known as “Accuracy Class”

IEC/AS Standard 62053-11 covers Accuracy Class 0.5, 1.0 & 2 for electromechanical meters for active energy (watt-hours) which means the accuracy as a percentage from reading based on full load conditions and unity power factor. However the accuracy deteriorates under lower load conditions, power factor less than unity along with the presence of harmonics.

IEC/AS Standard 62053-21 covers Accuracy Class 1.0 & 2 for static/electronic meters for active energy (watt-hours) which means the accuracy as a percentage from reading based on full load conditions and unity power factor. However the accuracy deteriorates under lower load conditions, power factor less than unity along with the presence of harmonics.

IEC/AS Standard 62053-22 covers a higher Accuracy Standard of 0.2S and 0.5S for static/electronic for active energy (watt-hours) providing a higher “Accuracy Standard” under full load conditions and unity power factor in addition to better accuracy readings at much lower load currents, power factor conditions less than unity along with the presence of harmonics.