APPLICATION OF DC MOTOR
As we all know that dc motor is the motor which converts the electrical
energy into mechanical energy. Because of this energy, we can use this
motor in number of applications. So we have discussed the application
of different types of DC motor.
Application of dc series motor
• DC series motor is suitable for both high and low power drives, for
fixed and variable speed electric drives. This type of motor has simple
construction. Also, it is easy for design and maintenance.
• Because of its high starting torque, it is widely used in the following
fields;
APPLICATION OF DC MOTOR
1.Cranes and hoists:
DC series motors are used in cranes and hoists due to their excellent starting
torque and ability to handle heavy loads. In a crane or hoist application, the
DC series motor is connected to a power supply .The power supply provides
the DC voltage to the motor, and the motor provides the torque to lift and
move the load. The DC series motor provides high torque at low speeds,
making it ideal for lifting and moving heavy loads.
2.Electric power tools:
DC series motors are used in various electric power tools, such as drills, saws,
and grinders. In an electric power tool application, the DC series motor is
connected to a power supply and a switch. The power supply provides the DC
voltage to the motor, and the switch turns the motor on and off. The DC series
motor provides high starting torque and excellent speed control, making it
ideal for applications requiring high power and precision.
APPLICATION OF DC MOTOR
3.Elevators/lifts
Most elevators are propelled by the electric motor, with the aid of
counterweight, through a system of cables and sheaves. A standard ac/dc
motor is responsible for shifting the electrical power to mechanical power and
drives the traction cables and counterweighing the hoist system to offer the
smooth uninterrupted ride.
4.Traction:
DC series motors are used in electric vehicles, such as forklifts, electric buses,
and trains. In an electric vehicle, the DC series motor is connected to a battery
and controller. The battery provides the DC voltage to the motor, and the
controller regulates the current flowing through the motor to control its speed
and torque. The DC series motor provides high starting torque, making it
ideal for heavy-duty applications.
APPLICATION OF DC MOTOR
5.Air compressors
They are devices that convert power into kinetic energy by compressing
and pressurizing air. They are used in variety of tasks such as powering
tools, inflating tires, operating pneumatic equipment, cleaning and
painting.
Electric motor are widely used to provide the power to drive the
compressor. As a prime mover the motor needs to supply sufficient
power to start the compressor, accelerate it to full speed and keep the
unit operating under various design conditions.so due to high starting
power and full speed, three phase induction motor is used.
APPLICATION OF DC MOTOR
Application of dc shunt motor
DC shunt motors are one of the most common types of DC motors, and they
are widely used in various applications. A DC shunt motor has a field winding
in parallel with the armature winding, and its speed can be varied by adjusting
the voltage to the armature. Here are some of the common applications of DC
shunt motors and why they are used:
1.Conveyor belts:
DC shunt motors are used in conveyor belts for their ability to provide
constant speed and high torque at low speeds. In a conveyor belt application,
the DC shunt motor is connected to a power supply and a controller. The
power supply provides the DC voltage to the motor, and the controller
regulates the current flowing through the motor to control its speed. The DC
shunt motor provides constant speed and high torque, making it ideal for
applications requiring continuous and reliable operation.
APPLICATION OF DC MOTOR
2.Pump and fan applications:
DC shunt motors are used in various pump and fan applications for their
ability to provide constant speed and high torque. In a pump or fan
application, the DC shunt motor is connected to a power supply and a
controller. The power supply provides the DC voltage to the motor, and the
controller regulates the current flowing through the motor to control its speed.
The DC shunt motor provides constant speed and high torque, making it ideal
for applications requiring continuous and reliable operation.
3.Textile industry:
DC shunt motors are used in the textile industry for various applications such
as spinning, weaving, and knitting. They are preferred over other types of
motors because of their excellent speed regulation and torque control, making
them ideal for maintaining a constant tension in the textile materials.
APPLICATION OF DC MOTOR
4.Paper mills:
DC shunt motors are used in paper mills for various applications such
as pulping, drying, and rewinding. They are preferred over other types
of motors because of their excellent speed regulation and torque control,
making them ideal for maintaining a constant tension in the paper web.
5.Printing presses:
DC shunt motors are used in printing presses for their ability to provide
constant speed and high torque at low speeds. In a printing press
application, the DC shunt motor is connected to a power supply and a
controller. The power supply provides the DC voltage to the motor, and
the controller regulates the current flowing through the motor to control
its speed. The DC shunt motor provides constant speed and high torque,
making it ideal for applications requiring continuous and precise
operation.
EFFICIENCY OF A DC MOTOR
The efficiency of a DC motor is defined as the ratio of output
power to the input power.
Mathematically,
Efficiency =(Power Output/Power Input)×100%
η =Pout/Pin×100%...........................................................(1)
Since,
Power input, Pin=Power Output(Pout)+Losses
Therefore,
Efficiency η=PoutPout+losses×100%..........................................(2)
EFFICIENCY OF A DC MOTOR
Condition for Maximum Efficiency of DC Motor
The efficiency of a DC motor is not constant but varies with the load.
Consider a shunt motor (as shown in the figure) drawing an armature current
of Ia amperes and the back emf is Eb.
The mechanical power developed by the motor is (neglecting the mechanical
losses),
Pm=Pout=Eb*Ia
EFFICIENCY OF A DC MOTOR
EFFICIENCY OF A DC MOTOR
The efficiency of the motor will be maximum, if the denominator of the
eqn. (3) is minimum. Hence, to determine the condition for maximum
efficiency, differentiating the denominator of the eqn. (3) with respect to
armature current and equating it to zero, i.e.
EFFICIENCY OF A DC MOTOR
Therefore, the maximum efficiency occurs in a DC motor when the
variable losses become equal to the constant losses for the motor.
EFFICIENCY OF A DC MOTOR
The armature current corresponding to maximum efficiency is
given by,
EFFICIENCY OF A DC MOTOR
Numerical Example
A 10 kW DC shunt motor has the following losses at full load
Mechanical Losses = 300 W
Iron Losses = 400 W
Shunt field Cu loss = 100 W
Armature cu loss = 500 W
Calculate the full-load efficiency of the motor and armature
current corresponding to maximum efficiency if the armature
resistance is 0.25 Ω.
EFFICIENCY OF A DC MOTOR
Solution
EFFICIENCY OF A DC MOTOR
EFFICIENCY OF A DC MOTOR
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