Q. Open-circuit and load characteristics of generator?

The open-circuit and load characteristics of a separately excited dc generator, along with its schematic diagram of connections, are shown in Figures (a) and (b). It can be seen from the form of the external volt-ampere characteristic, shown in Figure (c), that the terminal voltage falls slightly as the load current increases. Voltage regulation is defined as the percentage change in terminal voltage when full load is removed, so that, from Figure(c) it follows that

Because the separately excited generator requires a separate dc field supply, its use is limited to applications in which a wide range of controlled voltage is essential.