In this paper, a new testing process will be applied to examine the accuracy of the power system digital relay in terms of the embedded analog-to digital converter.  As the power system is based on an analog waveform, the digital relay has to digitize the power waveform for further analysis. However, the level of accuracy in digitizing will reflect the digital relay operation in identifying system abnormalities.  With many parameters that define the analog-to-digital converter, the effective number of bits could be one of the most important performance tests.  Yet, classical testing is based on signal-to-noise ratio components (SNR), whose coefficients are driven via the frequency domain (Fourier transform). The converter output digital waveform is extremely sensitive to noise. This makes the testing process longer in terms of time and more complex in terms of compilation.  In this work, an automated evaluation process based on a wavelet transform will be applied to test the power relay analog to digital converter's effective number of bits in less time and complexity.