Phase Compensation
The CT introduces an additional phase change between the current and voltage signal, which must be compensated. This compensation is performed by delaying the voltage samples by the same time that the CT delays the current samples. The phase compensation that is needed is measured during calibration.
A simple sample-by-sample delay provides a delay in single-sample steps. The fractional delay is implemented through a single-tap FIR filter to provide a delay from minus to plus 0.5 samples (see Figure 10).