Compound-wound DC generators are a type of direct current (DC) generator used to convert mechanical energy into electrical energy. These generators have both series and shunt field windings, combining the features of both series and shunt generators. This results in certain characteristics that make them suitable for specific applications. Here are the characteristics of compound-wound DC generators:
Voltage Regulation: Compound-wound generators are known for their good voltage regulation characteristics. This means that they are able to maintain a relatively stable output voltage even when the load on the generator changes. This is achieved by the interaction of the series and shunt field windings.
Self-Excitation: Like shunt-wound generators, compound-wound generators are also self-excited, meaning they can establish their own field current without the need for an external source. This is due to the shunt field winding.
Flat Compound Characteristics: The compound-wound generator's voltage regulation can be further classified into two types: cumulative compound and differential compound. Cumulative compound generators have a positive slope, meaning their terminal voltage increases with load. Differential compound generators, on the other hand, have a negative slope, resulting in a decrease in terminal voltage with increased load.
Stability: Compound-wound generators are more stable than series-wound generators. The presence of the shunt field winding helps in stabilizing the voltage regulation and preventing excessive fluctuations in voltage.
Applications: Compound-wound generators are commonly used in applications where a relatively constant voltage output is required, even with varying loads. They find use in industrial processes, battery charging, and other applications where stable power supply is crucial.
Compounded for Starting and Running: Compound-wound generators can be designed to provide higher initial starting torque, making them suitable for applications that require high starting currents, such as in electric traction systems.
Over-Compounding: Some compound-wound generators can be designed to exhibit over-compounding. This means that their voltage increases even more than the rated value at full load. This characteristic is useful in applications where long transmission lines are used, as the higher voltage helps compensate for the voltage drop along the line.
Complex Design: The design of compound-wound generators is more complex than that of shunt or series generators due to the combination of both field winding types. This complexity can sometimes make their maintenance and control more intricate.
In summary, compound-wound DC generators offer a compromise between the characteristics of shunt and series generators. They provide good voltage regulation, stability, and the ability to handle varying loads, making them suitable for a range of applications where consistent and reliable power supply is essential.