The power system is a sophisticated system which consists of many stages (as seen in Figure 1-1 [1]). It is designed to deliver the electricity from the power plant to the consumers through transmission lines. The last stage is where the voltage level is stepped down from medium (MV) to low (LV) in a distribution substation using step down transformers to transfer power to the users. In addition, the distribution substation must be protected against faults otherwise, the faulted component would not affect the operation of the network. There are multiple protection devises that can be used such as circuit breakers, protection relays, fuses, and instrument transformers [2].
Figure 1‑1: The Stages of the Power System [1]
Further introductions are presented in the following sections:
