Applications of DC Generators

There are various types of dc generators available for several types of services. The applications of these dc generators based on their characteristic are discussed below:

APPLICATIONS OF SEPARATELY EXCITED DC GENERATORS

These types of dc generators are generally more expensive than self-excited dc generators because of their requirement of separate excitation source. Because of that their applications are restricted. They are generally used where the use of self-excited generators are unsatisfactory.

I. Because of their ability of giving wide range of voltage output, they are generally used for testing purpose in the laboratories.

II. Separately excited generators operate in a stable condition with any variation in field excitation. Because of this property they are used as supply source of dc motors, whose speeds are to be controlled for various applications. Example- Ward Leonard Systems of speed control.

APPLICATIONS OF SHUNT WOUND DC GENERATORS

The application of shunt generators are very much restricted for its dropping voltage characteristic. They are used to supply power to the apparatus situated very close to its position. These type of dc generators generally give constant terminal voltage for small distance operation with the help of field regulators from no load to full load.

I. They are used for general lighting.

II. They are used to charge batteries because they can be made to give constant output voltage.

III. They are used for giving the excitation to the alternators.

IV. They are also used for small power supply.

APPLICATIONS OF SERIES WOUND DC GENERATORS

These types of generators are restricted for the use of power supply because of their increasing terminal voltage characteristic with the increase in load current from no load to full load. We can clearly see this characteristic from the characteristic curve of series wound generator. They give constant current in the dropping portion of the characteristic curve. For this property they can be used as constant current source and employed for various applications.

I. They are used for supplying field excitation current in dc locomotives for regenerative breaking.

II. This types of generators are used as boosters to compensate the voltage drop in the feeder in various types of distribution systems such as railway service.

III. In series arc lightening this type of generators are mainly used.

APPLICATIONS OF COMPOUND WOUND DC GENERATORS

Among various types of dc generators, the compound wound dc generators are most widely used because of its compensating property. We can get desired terminal voltage by compensating the drop due to armature reaction and ohmic drop in the in the line. Such generators have various applications.

I. Cumulative compound wound generators are generally used lighting, power supply purpose and for heavy power servicesbecause of their constant voltage property. They are mainly made over compounded.

II. Cumulative compound wound generators are also used for driving a motor.

III. For small distance operation, such as power supply for hotels, offices, homes and lodges, the flat compounded generators are generally used.

IV. The differential compound wound generators, because of their large demagnetization armature reaction, are used for arc welding where huge voltage drop and constant current is required.

At present time the applications of dc generators become very limited because of technical and economic reasons. Now a days the electric power is mainly generated in the form of alternating current with the help of various power electronics devices.