Several tools have been used over the years to analyze electromagnetic transients in power systems. The digital computer is the most popular tool, although TNAs and the new generation of real-time digital systems are also used, mainly in applications for which either a very high-speed or a real-time simulation is required. Many techniques have been developed to solve electromagnetic transients using a digital computer. They can be classified into two main groups: frequency-domain and time-domain techniques. The subject of this paper is the digital simulation of electromagnetic transients in power systems using a time-domain technique.