This application report demonstrates a digital technique to compensate and calibrate the phase shift of a current (or voltage) transformer used in electric power or energy measurement. Traditional analog compensation is replaced by a digital finite impulse response (FIR) filter. A technique emulating a non-unity power factor (non-UPF) load makes the calibration fully automatic. The calibration time is greatly reduced and it is more accurate and consistent. Use of emulation removes the bulky expensive non-UPF load.
The 16-bit RISC MSP430 mixed-signal processor from Texas Instruments is an effective
means of handling the otherwise demanding computational requirements.
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