It is common in the submetering market to use simple terms to express the accuracy of electric energy meter (such as 0.2%), but the reality is very complicated. This article summarizes the common meter and current transformer (CT) accuracy standards, as well as overall system accuracy. It explains how the system accuracy (meter with CTs) can be much worse than just the meter accuracy or even the naïve addition of the meter and CT accuracies (a 0.2% meter with 0.3% CTs may not result in 0.5% accuracy).

For the full application note, see the PDF: AN-136: Metering System Accuracy

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