Applications of DC Machines

At present, a large amount of electrical energy is generated in the form of alternating current. Consequently, the use of DC machines (motors or generators) has become limited. However, dc machines are still used in several applications like for supplying excitation systems of alternators, in electrolytic processes, welding processes, etc.

Applications of DC Generators

There are different types of DC generators are available for the various types of applications. The applications of various types of DC generators based on their characteristics are as follows −

Separately Excited DC Generators

A separately excited DC generator requires an independent external DC source for the excitation of field winding. Thus, it is expensive and being rarely used. Following are some application of separately excited DC generators −

• These are able to produce a wide range of voltage output, they are primarily used in laboratory and commercial testing.
• These are used in speed regulation tests.
• These generators operate in a stable condition with any change in field excitation. Therefore, they are also used in supplying power to the DC motors, whose speed being to be controlled.

Series DC Generators

A series DC generator has limited applications. Some of the applications of a series DC generator are as follows

• The rising characteristics of a series DC generator makes it suitable for voltage boosting applications in the feeders in the various types of distribution systems.
• A series DC generator has the tendency to supply constant load current. Hence, several series generators can be connected in series to provide high voltage DC power transmission at constant load current.
• The series DC generators are also used in supplying field excitation current in DC locomotives for regenerative breaking.
• The series generators also find applications in series arc lightening.

Shunt DC Generators

A shunt DC generator produces constant terminal voltage for small distance operations. Therefore, these are used in following applications

• They are used for battery charging applications.
• Shunt DC generators with field regulators are used for lighting and power supply purposes.
• Use for giving excitation to the alternators.

Compound DC Generators

The compound DC generators are used in following applications

• The over compounded generators have ability to compensate voltage drop in the transmission lines and tends to maintain constant voltage at the consumer's end. Therefore, the over compounded generators are used in supplying loads through long transmission lines.
• Cumulative compound generators are used for supplying power to DC motors.
• Cumulative compound generators are used for lighting, power supply purposes and for heavy power services, etc.
• The differential compound generators are used for arc welding purposes where a large voltage drop and constant current is required.

Applications of DC Motors

The applications of different types of DC motors are given below −

Series DC Motor

• Series DC motors are used in applications where high starting torque is required.
• Series DC motors are used in cranes and hoists.
• Series DC motors are used in electric tractions.
• They are used in air compressors.
• They are also used in vacuum cleaners.
• Series DC motors are also used in sewing machines, etc.

Shunt DC Motor

• Shunt DC motors are used in applications that require constant speed.
• Shunt DC motors are used for driving lathe machines.
• These are also used in centrifugal pumps and blowers.
• These are used in fans, conveyors, and spinning machines.
• These DC motors are also used in lifts.

Compound DC Motor

• Compound DC motors are used in those applications which require high starting torque and constant speed.
• Used in printing presses.
• They are also used in shears.
• They are used in elevators and lifts.
• Compound DC motors are also used in rolling mills and heavy planners, etc.