DC Motor - Definition, Working Principle, Types, Uses, FAQs

We will discuss in this article DC motor, DC motor diagram, working principle of dc motor, the principle of and application of dc motor, construction of dc motor, construction of dc machine, dc motor parts, motor concept, bldc (bldc full form, brushless Direct current), pmdc motor, motor diagram, etc.

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1. DC motor construction and working -
2. Applications of DC motors:-
3. Disadvantages of DC motor:-

What is a DC machine?:- DC machine definition, “In the rotating electrical machine an electro-mechanical energy conversion takes place is called a DC machine.” In all the rotating electrical machines, a change in flux is associated with the mechanical motion to cause electromechanical energy conversion. When mechanical input energy is converted into electrical energy, the machine is called the generator and when the electrical energy is converted into mechanical energy, then the machine is called a DC motor.

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Construction of DC machine:- Basic structure of DC machine.

The electric machine has two parts

• The stator of the machine does not move and normally, it is the outer frame of the machine.

• Rotor: The rotor is free to move and normally it is the inner part of the machine.

The machine has two types of winding

• Field winding:- The winding through a current is passed to produce the main flux is called the field winding.

• Armature winding:- The winding in which voltage is induced is called the armature winding.

This is the construction details of the DC machine.

The working principle of a DC machine:- principle of DC machine is that when a current-carrying conductor is put in a magnetic field a force is produced on it. We know that DC machines are of two types DC motor and DC generator. So, we discuss the working of a DC machine as a DC motor.

• In a simple way, the meaning of motor is that it is a type of machine which converts electrical energy to mechanical energy.

• Motor definition or define the electric motor and motor concept “ a machine that converts the electrical energy into mechanical energy is called the motor machine or machine motor”. According to electromagnetic induction when any current coil is placed in a magnetic field then magnetic torque works on the coil and at a constant position, the current-carrying coil starts rotating in the motoring process. Electrical energy is provided through the terminals of stationary or moving coil and produces torque due to stationary or moving magnetic field and by this torque, it rotates the rotor and converts the electrical energy into mechanical energy and received on the rotor shaft in the form of mechanical energy. There are two types of motor AC motor and DC motor. Did you know, who invented the electric motor or DC motor? The electric motor is invented by William Sturgeon, who was the first man who invented the first electric motor with the commutator. Thomas Davenport of Vermont was the first who invented the first official battery electric power.

• What is a DC motor:- DC motor is a type of machine which converts the direct current nature of electrical energy into mechanical energy. This is the DC motor definition. A current that always flows in the same direction through an electrical device is called a direct current ( DC ) and the dc motor’s full form is a Direct current motor. That’s all the DC motor theory.

• The working principle of DC motor:-We explain the working principle of DC motor, as when a current-carrying conductor is put in a magnetic field a force is produced on it. Let us consider one such conductor placed on a slot of the armature and suppose it is acted upon by a magnet from the north pole of the motor. By applying the left-hand rule it is found that the conductor has a tendency to move to the left-hand side. Since the conductor is in a slot on the circumference of the rotor, the force (F= Bil) acts in a tangential direction to the rotor.

DC motor construction and working -

• Construction of dc motor:- The design of an electrical motor is shown in fig. A motor basically consists of a coil placed in a magnetic field. The DC electric motor parts are
• Stator
• Shaft
• Brushes
• Commutator
• Armature
• Poles
• Field winding
• Rotor

DC motor components:- The two main components of a DC motor is the stator and armature.

The coil is formed by winding of many turns over a soft iron core. DC motor winding consists of two windings namely field winding and armature winding. The core and coil together form an armature. The dc motor armature is fixed on the shaft on the motors and kept between the poles of a strong magnet. The two free ends of coils are connected to the two halves of a metallic split ring ( a ring split into two separate parts ). The split ring forms what is called the split ring commutator or simply commutator. When the shaft rotates, the commutator and coil rotate with it. Two carbon brushes, B₁ and B₂, press against two halves C₁ and C₂ of the commutator. A potential difference is applied to the brushes by connecting them to a source of the source DC, For example, a battery.

• DC motor working:- How does a DC motor work? let’s explain the working of the DC motor, The brush B₁ is connected to the positive terminal of the battery, and B₂ is connected to the negative terminal. (But, what are the materials used for brushes in dc machines, Carbon is used for brushes.) So, a current flows in the coil along ABCD (A→B→C→D). Shows the position of a coil after a half rotation from the initial position. As a result of the rotation, the brushes with which two halves of the commutator in the two halves of the commutator were in contact got interchanged. This has reversed the battery connections to the two arms of the coil. Therefore, the current now flows along DCBA. That is the direction of current in two arms of the coil has got reversed. Such changes take place for each half rotation. In this way, the commutator changes the direction of the current in the coil after each half rotation

The two arms of the coil carry a current in a magnetic field. So, each arm experiences a force. The directions of the forces are shown by arrows in fig. In the position shown upward, the arm AB experiences a downward force, while the arm CD experiences an upward force. This may be verified by using Flemming’s left-hand rule. The coil rotates in the core and is reversed, as explained above. Using Flemming’s left-hand rule, we find that arm AB now experiences an upward force, and the arm experiences a downward force. So, the coil continues to rotate in the anticlockwise direction.

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If the commutator is not used, the direction of the current in an arm of the coil will always remain the same. So, the 3 direction of the force on the arm will not change, and the coil will not be able to complete one rotation. For example, when the arm AB is near the north pole, the downward force will turn it anticlockwise. And when it is near the south pole, the downward direction swings it back, clockwise. Thus the rotation will not be completed. This motor is known as a simple DC motor.

When a current-carrying conductor is placed in a magnetic field it experiences a force.

1. In the case of a DC motor, The magnetic field is developed by field current, i.e., the current flowing in the field winding.

2. The armature winding is connected to an external Dc source, hence it plays a current-carrying conductor placed in a magnetic field.

3. Due to the force exerted on it when placed in a magnetic field, it starts rotating.

4. The direction of rotation is decided by Flemming’s left-hand rule.

Characteristics of DC Motor:- The characteristics of DC motor depends on three Categories

• Speed characteristics:- If a graph is drawn between the speed of the motor ( N ) and Armature current (I) then it is known as speed (N/I) characteristics.

• Torque characteristics:- If a graph is drawn between the armature torque (?) and armature current (I) then it is known as torque ( ?/I) characteristics.

• Mechanical characteristics:- If a graph is drawn between the speed of the motor (N) and armature torque (?) then it is known as mechanical ( N/ ?) torque.

• Uses Of DC Motors:- We used dc motors in various fields

• DC series motor uses: Its high starting torque makes its part equally suitable for a wide range of traction applications. Industrial use are hoists, cranes, trolleys, cars, conveyors, Elevators, air compressors, vacuum cleaners, sewing machines, etc

• Uses of shunt Motors:- The shunt motor is used where constant speed is required and starting conditions are not severed full start the various applications of DC shunt motor are in leather machines centrifugal pumps, fans blowers, conveyors, lift machines, spinning machines, etc

NCERT Physics Notes :

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Applications of DC motors:-

Application of DC series motor:-It is a variable speed motor. The uses of this motor are in lifts, rolling mills, railway engines, cranes, trams, and electric traction. The starting torque of these motors is high.

Applications of DC shunt motors:-DC shunt motors are constant speed motors. The starting torque of shunt motors is not high. So, these motors are used in places where constant speed is required.

The use of these types of motors is in grinders, shapers, drilling machines, vacuum cleaners, and fans.

Applications Of DC compound motors:-Compound motors have low starting torque. These motors have constant speed at low loads. Therefore these machines are used, where load increase suddenly and work has to be done at high load.

Disadvantages of DC motor:-

(i) DC motor has a high cost.

(ii) We cannot use it in explosive and hazardous conditions because sparking may occur in the brushes.

(iii) Its maintenance is difficult.

DC motor function is to convert electrical energy to mechanical energy.

DC motor examples:- DC motor used in various places like electric fans, washing machines, etc.

Ceiling fan working principle:-The ceiling fan has a motor. The motor converts electrical energy into mechanical energy. The capacitor present in a ceiling fan torques up the electric motor, which makes it start and run. As soon as the electrical current passes through the motor (placed in the metal base), it enters into the wire coil of the motor and creates the magnetic field that further exerts force in a clockwise direction. So, the motor converts the electrical energy to mechanical energy and causes the fan to spin.

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