When you have completed this chapter, you will be able to: Describe how a microprocessor communicates with its peripherals. List the primary components found within the hardware of a numeric relay. Explain how analog busbar signals are converted into numeric values. Explain the cause of the aliasing of sampled signals. Describe how a digital filter works and why analog and digital filters are used in a numeric relay. Describe how values may be converted into phasor form using the discrete Fourier transform. In addition, you will have a comprehensive understanding of the operation of a numeric distance relay and a numeric current differential relay, which will make you feel confident and competent in dealing with these critical components in protection systems.