DC Machine

DC Machine

D.C. machines are the electro mechanical energy converters which work from a d.c. source and generate mechanical power or convert mechanical power into a d.c. power. These machines can be broadly classified into two types, on the basis of their magnetic structure.

DC Machine is an electro mechanical energy conversion device. There are two types of DC machines

• DC generator
• DC motor

DC generator converts mechanical power into DC electrical power, whereas, a DC motor converts DC electrical power into mechanical power.

The AC motor is invariably applied in the industry for conversion of electrical power into mechanical power, but at the places where the wide range of speeds and good speed regulation is required, like in electric traction system, a DC motor is used.

Application of DC Machines

Here are some applications of DC motor in different Forms,

• Series Motors

        The series DC motors are used where high starting torque is required, and variations in         speed are possible. For example – the series motors are used in Traction system, Cranes, air compressors, Vaccum Cleaner, Sewing machine, etc.

• Shunt Motors

        The shunt motors are used where constant speed is required and starting conditions are not severe. The various applications of DC shunt motor are in Lathe Machines, Centrifugal Pumps, Fans, Blowers, Conveyors, Lifts, Weaving Machine, Spinning machines, etc.

• Compound Motors

       The compound motors are used where higher starting torque and fairly constant speed is required. The examples of usage of compound motors are in Presses, Shears, Conveyors, Elevators, Rolling Mills, Heavy Planners, etc.

       The small DC machines whose ratings are in fractional kilowatt are mainly used as control device such in Techno generators for speed sensing and in Servo motors for positioning and tracking.

Applications of DC Generators

The applications of the various types of DC Generators are as follows:-

• Separately Excited DC Generators

•         Separately excited DC Generators are used in laboratories for testing as they have a wide range of voltage output.
•         Used as a supply source of DC motors.

• Shunt wound Generators

•         DC shunt wound generators are used for lighting purposes.
•         Used to charge the battery.
•         Providing excitation to the alternators.

• Series Wound Generators

•         DC series wound generators are used in DC locomotives for regenerative braking for providing field excitation current.
•         Used as a booster in distribution networks.
•         Over compounded cumulative generators are used in lighting and heavy power supply.
•         Flat compounded generators are used in offices, hotels, homes, schools, etc.
•         Deferentially compounded generators are mainly used for arc welding purpose.