Power measurement is important for various purposes such as revenue metering, power quality improvement, and direct load control. Various algorithms for power measurement have been proposed in the time domain, which implies a simple instrumentation, but more useful power formulations have been derived in the frequency-domain approach which would require appropriate sampling and measurement techniques to avoid long delay in processing voltage and current signals. The aim of this thesis to implement a measurement instrument that can measure the power components digitally and efficiently under sinusoidal and non-sinusoidal situations. We will use a high performance digital signal processing (DSP) chip and adopt a frequency domain based algorithm for the computation of power elements. The measurement system is expected to offer both high speed and accuracy, and can show wide spectra limited only by the sampling frequency.