The Engineering Projects

Wound Rotor Induction Motor

Hi friends, I hope you are fine and having fun. In my last article, we have discussed Squirrel Cage Induction Motor which is a type of 3 Phase Induction Motor.  Today, I am going to tell you about a Wound Rotor Induction Motor , which is also a type of 3 phase induction motor. This motor is the one which uses a wound rotor. I will tell about the construction of a wound rotor later in this article. A Wound Rotor Induction Motor is also known as slip ring induction motor.

I will tell you about the construction of Wound Rotor Induction Motor in the first section. In the second section, I would be throwing light on the operation and working principle of Wound Rotor Induction Motor. After that, I will tell you some of the key features and uses of Wound Rotor Induction Motor.

Construction of Wound Rotor Induction Motor

As in other induction motors, the basic parts are stator and rotor. Stator of this motor is the same as the one used in squirrel cage induction motors.  Rotor is the part which distinguishes it from other induction motors. Let me give you a brief idea of stator first and then I will tell you about the structure of rotor.

Stator of Wound Rotor Induction Motor

• As the name implies, stator is the stationary part of Wound Rotor Induction Motor.
• The stator and rotor are separated from each other by a small air gap.
• Stator of any type of induction motor is a cylindrical frame inside which rotor rotates.
• The cylindrical frame has grooves on its internal periphery to carry electrical circuitry.
• The stator winding is excited by AC supply.
• That was the basic structure of stator, now let’s talk about rotor.

Rotor of Wound Rotor Induction Motor

• In Wound Rotor Induction Motor, the rotor has a 3 phase winding similar to stator winding.
• Rotor is also cylindrical in shape and has slots to carry winding.

• The winding is placed evenly on slots of the rotor.
•  are connected to 3 slip rings.
• These slip rings are mounted on the shaft.
• Each phase is connected to one of the three slip rings. These slip rings are associated with brushes.
• The three slip rings rotate with rotor, while brushes remain stationary.
• This is all about construction of rotor. Now let’s discuss the working principle.

Working of a Wound Rotor Induction Motor

• The working principle of Wound Rotor Induction Motor is as same as in any other induction motor.
• AC supply is given to stator winding, which produces a magnetic field that is rotating because of the time changing AC supply.
• The flux lines of the magnetic field will cut the rotor and induce an emf according to Faraday’s law.
• The induced emf will induce a current that will generate another magnetic field. This magnetic field is called rotor magnetic field.
• The magnetic field of stator and the magnetic field of rotor will interact and give rise to a torque which will turn the rotor.

This motor is different because the rotor windings are connected to external resistances through slip rings. The speed and torque can be adjusted in these motors by changing resistance.  Now I am going to tell you about some of the key features of these motors.

You may also like to read:

• Introduction to Induction Motor.
• Single Phase Induction Motor.
• 3 Phase Induction Motor.
• Introduction to Synchronous Motor.

Key Features

Some of the features of wound rotor induction motors are as under:

Speed Control

• It is possible to control the speed of such motors. The torque can also be controlled.

High Starting Torque

• These motors have high starting torque.

Maintenance

• Wound Rotor Induction Motor require more maintenance because of slip rings and brushes.

Cost

• Such motors are expensive than other induction motors. The maintenance cost also counts.

Low Starting Current

• This motor draws less current at start as compared to squirrel cage induction motors.

Efficiency

• Wound Rotor Induction Motor are less efficient than squirrel cage induction motors.

Power Factor

• These motors have a low power factor.

Now I am moving towards the last section, in which I am going to tell you all about some of the application areas of Wound Rotor Induction Motor .

Applications

The uses and applications of this induction motor are:

• They are used in areas where high starting torque is required. And where squirrel cage induction motors cannot be used because of their high starting currents.
• These motors are used with high inertia loads.
• Wound Rotor Induction Motor is used in applications which require smooth start and adjustable speed.
• Some of the applications of this motor include cranes, mills, hoists and conveyors.
• Wound rotor induction motor is also used in fans, blowers and mixers.
• They are used in large pumps in water industry.

Squirrel Cage Induction Motor

Hello Friends, I hope you all are fine and doing great. I am here with another article on Induction Motors. In this article I am sharing some basic knowledge on Squirrel Cage Induction Motor. In my previous article named as 3 Phase Induction Motor, I have given a brief overview of this Squirrel Cage Induction Motor.

A 3 phase induction motor has two types based on the rotor construction, named as: Squirrel Cage Induction Motor and Wound Rotor Induction Motor. Former is cheaper and broadly used as it requires less maintenance than later one. Firstly, I am going to tell you about the structure of squirrel cage induction motor. Afterwards I will cover the working principle and features of Squirrel Cage Induction Motor. In the last sections, I will share some advantages and uses. In simple words, the type of 3 phase induction motor which uses a squirrel cage rotor is called squirrel cage induction motor.

Construction of Squirrel Cage Induction Motor

All induction motors have a rotor and a stator. Basically, it is the construction of rotor which makes Squirrel Cage Induction Motor different from Wound Type Induction Motor. Stator is same in both types of motors. Let’s first talk about stator of Squirrel Cage Induction Motor:

Stator of Squirrel Cage Induction Motor

• Stator is that component of motor which is stationary.
• It is the outer most frame in which rotor is placed.
• It has grooves on internal circumference to carry electric circuitry. This circuitry is excited by 3 phase supply.
• The 3 phase winding circuit is placed on the slots. These winding are 120 degrees apart connected as star or delta configuration.
• Now let’s move towards the construction of rotor.

Rotor of Squirrel Cage Induction Motor

• Rotor is the rotating part of a motor. It contains a cylindrical core.
• The rotor core is made in lamination to reduce eddy currents.

• Squirrel cage type rotor consists of bars of copper that we call conductors.
• The copper bars or conductors are longer than the rotor and are fixed in grooves of rotor core.
• These extended conductors are short circuited with each other by means of copper rings on each sides.
• Also rotor is sometimes provides with fans on each side for cooling purposes.
• This type of construction of bars and end rings is similar to a squirrel cage on which it is named.
• That was all about rotor construction. Other than rotor and stator, a motor has also other parts to support and protect the assembly.

You may also like to read:

• Introduction to Induction Motor.
• Single Phase Induction Motor.
• 3 Phase Induction Motor.
• Introduction to Synchronous Motor.

Working of a Squirrel Cage Induction Motor

In this section, I will share the working of a squirrel cage induction motor with you guys.

• When the winding of stator are given a 3 phase AC supply, a current will start flowing through it.
• This 3 phase AC will give rise to a rotating magnetic field in the rotor.
• The speed of rotation of this magnetic field can be found from the frequency of AC supply and number of poles.
• This speed is the synchronous speed of motor.
• The rotating magnetic field of stator will induce voltage in rotor because its flux lines cut through the rotor. This induced voltage will induce current in rotor winding and another magnetic field will be generated which is rotor’s magnetic field.

As you all know, that a current carrying conductor experiences a force on it in presence of a magnetic field. The rotor will also experience a force which would start turning it. This force will produce a torque and rotor will rotate.

Key Features

Now I am mentioning some important features of a squirrel cage induction motor. I will talk about speed, starting current, direction of rotation, slip and power factor. First on the list is speed.

Speed

A squirrel cage induction motor generally operates at a constant speed. This speed is synchronous speed.

Starting Current

Such motors require high starting currents. Which may result in fluctuations in voltage.

Direction of Rotation

The direction of rotation of these motors can be reversed if you interchange two power lines out of three.

Slip

As for other induction motors, the slip is defined as the difference in speed of rotating magnetic field of stator and rotating speed of rotor. The speed of rotation of magnetic field is called synchronous speed. Slip is expressed as a ratio with synchronous speed or in percentage.

Power Factor

Power factor is the ratio of actual power to apparent power. It is expressed in percentage. The power factor is low when motor is running at no load and it is high when motor is operating at full load.

Advantages

In this part, I will tell you guys some of the advantages of squirrel cage induction motor.

• Squirrel cage induction motors are:
  • Cheap
  • Robust
  • Rugged
  • Require less maintenance
• Due to cage structure of rotor, they require less material. So copper losses decrease.
• Due to absence of brushes, the chances of spark are reduced.
• These motors are provided with fans, so less heat is generated.

Now I am moving towards the last segment of my article, where I will tell you some of the uses of squirrel cage induction motors.

Uses

This type of motor finds its uses in industries because of their cost. They are extensively used in industrial applications instead of wound type induction motor. They are used in applications where low starting torque is needed. Such motors may also be used as generators.

Introduction to Synchronous Motor

Hi friends, hoping everyone is fine and enjoying their lives. I am here today with an article on Introduction to Synchronous Motor. You all already know that motor is a mean of converting electrical energy into mechanical energy. Synchronous motor is the type of motor in which the rotating speed of rotor is same as the rotating speed of magnetic field. In other words, rotor rotates at the synchronous speed unlike Induction Motor, which we have discussed in Introduction to Induction Motor.

In this article, I will share the Introduction to synchronous motor with you guys. First things first, I am telling you about its construction and working in first two segments of my article. While later I would be throwing some light on its key features followed by methods of starting and areas of application. So, let's have a look at Introduction to Synchronous Motor:

Construction - Introduction to Synchronous Motor

• In Introduction to Synchronous Motor, we will first talk about the construction of synchronous motor.
• Talking about its construction, the basic structure is same as of other motors.
• Stator and rotor are the main parts while frame is the cover.
• Stator and rotor both make up the electric and magnetic circuitry of Synchronous motor.
• I will tell you about the stator first:

Stator of Synchronous Motor

• As the name suggests, stator is the stationary part of motor.
• It is the outer frame which is cylindrical in shape.
• This cylindrical frame is laminated and has slots to carry winding circuitry
• Stator of this motor is supplied 3 AC power.
• The winding circuit of stator is called stator winding.

Now, I will tell you about the rotor of a synchronous motor.

Rotor of Synchronous Motor

• Rotor is the rotating part, which rotates exactly at the same speed as the stator magnetic field.
• It is also cylindrical in shape and it is the shaft of the motor from where output load is connected.
• It rotates in the stator frame which is separated by an air gap.
• Rotor of a synchronous motor is excited by a DC source.

Frame of the motor protects and cover the whole assembly. It can either be built in vertical or horizontal shape and the type of covering depends on its area of use. That was all about construction of a synchronous motor. The next on my list in Introduction to Synchronous Motor is working principle and operation of this motor.

Working of Synchronous Motor

Let’s now talk about the working of these motors briefly. The operation of a synchronous motor is basically that the rotor tries to follow the rotating magnetic field of stator and rotates at a speed approaching to it. This motor is a doubly excited machine. The rotor winding is excited by a DC source while the stator winding is excited through an AC source.  A 3 phase rotating magnetic field is produced by stator winding due to 3 phase AC. And a constant magnetic field is produced by rotor winding.

At some instant of rotation, the poles of two magnetic fields may attract each other while at some other instant, they repel each other. The rotor will not start rotating due to these interactions due to its inertia. So an external mean will compensate and provide initial rotation to the rotor. Once the rotor starts moving at the synchronous speed, this external source is shut off.

In synchronous motor, the magnetic field of rotor is produced not by the magnetic field of rotor through induction. Instead the magnetic field is generated by direct current supply. Therefore, the air gap between rotor and stator is not kept very small as in the case of induction motors. Next thing in Introduction to Synchronous Motor is the important features of this motor.

Key Features of a Synchronous Motor

In this segment of my article, I am sharing some features of this type of motor which differentiates it from other motors.

Speed

• Generally, the speed of ranges from 150 rpm to 1800 rpm. The speed remains constant from no load to full load and can be found from the following formula:

N_s = 120 * f / p

Where f = frequency of AC supply

                p= no of poles

The speed is synchronous speed. It does not depend on load conditions.

Starting Torque:

• Synchronous motors need some external method for starting as it has no starting torque. The next section of this article gives the commonly used methods to start it.

Rating

• The power rating of synchronous motors is 150kW to 15MW.

Efficiency

• Synchronous Motors are highly efficient machines. Their efficiency is much greater than induction motors.

Cost

• Synchronous motor is costly as compared to induction motor of same rating.

Power Factor Correction

• Synchronous motors have a leading power factor therefore used in areas where power factor correction is needed.

Maintenance

• This motor uses brushless excitor which decreases the maintenance problem of this machine.

Now, I am moving towards last two parts of this Introduction to Synchronous Motor, where I am going to share some knowledge about the methods of starting and uses of these motors.

Methods of Starting a Synchronous Motor

As I told you earlier in my section on key features, synchronous motor cannot self start as it has no starting torque. Therefore to overcome this problem different ways are used. Some external mean is used at start for bringing up the speed up to synchronous speed. The three main ways are as under:

1. Reducing frequency of stator to a safe starting level.
2. Using external prime mover.
3. Using damper windings.

These are the ways which are used to start a synchronous motor.

Uses and Areas of Application

Introduction to Synchronous Motor won't be complete unless we have a look at its uses and areas of Application, I am sharing some of the uses of synchronous motor which are given below.

• The basic use of a synchronous motor is “power factor correction” that means to increase the power factor of a system.
• Synchronous motors are also used in voltage regulation. For example, they are used at the end of transmission lines to regulate voltage.
• Synchronous motors are commonly used for low speed, high power loads. Their application area is constant speed constant load drives.
• With VFD (variable frequency drive), synchronous motors are used to attain a range of speeds.
• Synchronous motors are used in air and gas compressors and vacuum pumps.
• They are also used in blowers, exhausters and fans.
• Such motors also find their application in crushers, mills and grinders.

So that's all about the Introduction to Synchronous Motor and I hope you have enjoyed it. I will surely gonna post more tutorials on Synchronous Motor. So, take care and have fun !!! :)

3 Phase Induction Motor

Hi fellows! Hoping everyone is fine and doing great. Today, I am going to write about 3 Phase Induction Motor. As I mentioned earlier in my article on Introduction to Induction Motors, there are two types of Induction Motors, Single Phase Induction Motor and 3 phase Induction Motor.

3 phase induction motor is the one which operates on three phase AC supply. It is the most commonly used motor for high load and industrial applications. I would discuss advantages of a 3 phase induction motor later in this article. Three phase induction motors are further divided into two types; Squirrel Cage Induction Motor and Wound Rotor Induction Motor based on the construction of rotor. First of all, I am going to discuss about the construction of 3 Phase Induction Motor and then I will throw some light on its working.

Construction of 3 Phase Induction Motor

Talking about its construction, like any other motor a 3 phase induction motor consists of a rotor and a stator. Let’s revise the basic knowledge about rotor and stator first.

• Rotor is the rotating part while stator is the stationary part of motor.
• Rotor is separated from the stator by a small air gap.
• Stator is actually a cylindrical frame inside which the cylindrical core of rotor rotates.
• The stator of motor has slots on its internal side to carry the winding circuitry. This circuit is supplied with AC power. This winding is called stator winding.
• As I told earlier, rotor is a cylindrical core which is laminated and it acts as the output shaft of motor.
• Rotor of motor has also slots to carry conductors. These conductors make up rotor winding.
• Now, I am going to discuss types of rotor.

Types of a 3 Phase Induction Motor

Based on the rotor construction, a 3 phase induction motor is further classified into two types:

• Squirrel Cage Induction Motor
• Wound Rotor Induction Motor

Squirrel cage induction motor is cheaper than wound type, and because of the absence of brush assembly it requires less maintenance due to less wear problems.

Squirrel Cage Induction Motor

• First I will talk about squirrel cage type of induction motor.
• The rotor of a squirrel cage type motor consists of bars of copper.
• These copper bars or conductors extend out from the rotor length and are fixed in slots of rotor core.
• The bars which are extended out are short circuited together by means of copper rings on each sides as shown in figure.
• This type of construction of bars and end rings is similar to a squirrel cage, from where the name comes. Next is the construction of a wound type induction motor.

Wound Rotor Induction Motor

• In wound rotor induction motor, there is a 3 phase winding which is similar to stator’s winding.
• This winding is placed uniformly on slots of the rotor.
• The endings of these windings are connected to 3 slip rings on the shaft.
• Each phase out of three phase is connected to one slip ring.
• The slip rings of each phase rotate with rotor and are further associated with brushes which are stationary. The construction is shown in figure.
• That’s all about construction and classification of 3 phase induction motor. Now let’s discuss about working principle.

Working Principle of 3 Phase Induction Motor

In this section of the article, I am going to talk over the working principle and operation of a 3 phase induction motor. Before diving into the details, let’s revise some basic concepts and laws that govern its operation.

Faraday’s Law:

• Faraday’s law is the basic law of electromagnetic induction which plays the most important part in the working of a 3 phase induction motor.
• According to which an emf is induced in a conductor when it is placed in a varying magnetic field or if the conductor is rotated in a magnetic field. In other words, emf is induced whenever there is a relative motion of the conductor and magnetic field.
• Also, if the conductor is a closed circuit, a current is produced termed as induced current.

Lenz’s Law:

• Following Faraday’s Law as explained earlier in the previous point, when an emf is generated in a conductor, its polarity would be such that it will produce current whose magnetic field will oppose the change that is producing current. This is called Lenz’s law.

Lorentz Force:

• Lorentz force is the force which is responsible to move the conductor in the magnetic field.
• Whenever, a current is flowing in a conductor in the presence of a magnetic field, the conductor will experience this force.

That was all about the basics, now I am going to throw light on its working and development of torque.

First of all, a 3 phase AC voltage is supplied to the stator windings due to which a 3 phase current starts flowing in it. These currents flowing in windings will produce a magnetic field that rotates due to AC oscillations. Now, the flux of this rotating magnetic field will cross the rotor conductors and a voltage is induced in them which depends on three factors; the relative speed of conductor and magnetic field, magnetic flux density and length of the conductor. The result of this induced voltage is the generation of induced current in rotor, which lags behind the rotor’s induced voltage. This leads to the production of rotor’s magnetic field. Finally, the torque induced is the scaled product of stator magnetic field and rotor magnetic field and the rotor of 3 phase induction motor starts rotating.

The rotor of induction motor never achieves the synchronous speed to keep itself rotating as I discussed in my article on Induction Motors. Next, I am going to give some equations and formulas for calculating synchronous speed, slip and rotor frequency of 3 phase induction motor.

• Let’s first talk about Synchronous speed. Synchronous speed is the speed of rotating magnetic field of stator. It is represented as n_s. If “f” is the frequency of AC supply and “p” is the number of poles then n_s = 2*f/p.
• Second term on the list is slip of induction motor. Slip is denoted by “p” and it is the difference of synchronous speed and rotors mechanical speed. If synchronous speed is n_s and rotor speed is n_r then s = (n_s - n_r). Slip is also expressed as a ratio per unit or as percentage of synchronous speed. This expression is used to find rotor speed, when slip of motor is known.
• Rotor frequency is also discussed for 3 phase induction motors. This frequency is directly proportional to the slip. Represented by f_r, it is expressed by the following formula: f_r = s * f

That was all about the working of a 3 phase induction motor, so before telling the advantages I am going to give a brief idea on its equivalent electric circuit.

Equivalent Circuit of a 3 Phase Induction Motor

A 3 phase induction motor is also called a rotating transformer as working principle of both are quite similar. So, the equivalent circuit is also similar to that of a transformer as shown in image. Right side of the image shows rotor circuit and left side is stator side.

• On the stator side, there is resistance and self-inductance in stator windings. R1 is the resistance of stator and X1 is stator reactance.
• E1 is the stator voltage. Er is the induced voltage in rotor windings while Vp is the applied voltage to the machine.
• On the rotor side, Rr is the rotor resistance and Xr is the rotor reactance.
• A_eff denotes the turn ratio of a transformer which associates E1 and Er.
• Xm is the magnetizing reactance.
• I1 is the stator current while Ir is the current in rotor.

In the last section of my article, I am gonna give some advantages of a 3 phase induction motor.

Advantages

• Let’s now take a look on the advantages of a 3 phase induction motor.
• 3 phase induction motors are simple and require easy maintenance.
• They are preferred because of low price.
• They can be used in rugged environments.
• A 3 phase induction motor is brushless so the problem of maintenance and wear is avoided.
• Speed of this motor can also be controlled.

   

Single Phase Induction Motor

Hi friends, I hope you all are fine and doing great with your lives. Today, I am gonna give you an Introduction of a Single Phase Induction Motor. As I previously mentioned in my article on Introduction to Induction Motors, there are two main types of Induction Motors, single phase induction motor and 3 phase Induction Motor. For information on three phase, you can read my article on 3 Phase Induction Motors. Now let’s talk about the definition of single phase induction motor.

A single phase induction motor is the one which operates on a single phase AC power source. This motor is used in the applications where requirement of power is low. It is generally used in domestic applications because of limited size and less power. Some of the uses include fans, washing machines, pumps, toys, vacuum cleaners, refrigerator compressors and in machine tools.

First I will tell you about its construction, followed by working principle and advantages. And in the last sections of this article, I will share some knowledge about the starting problem of a single phase induction motor and give a comparison of 3 phase and single phase induction motors. Let’s now take a look on construction of a single phase induction motor.

Construction of Single Phase Induction Motor

• The basic construction of Single Phase Induction Motor is similar to all other motors.
• A rotor and a stator are the two main components of Single Phase Induction Motor.

• We will have a look at both Stator and Rotor one by one below.
• So, first of all have a look at the functionality of Stator of Single Phase Induction Motor:

Stator of Single Phase Induction Motor

• The stator of a single phase induction motor is the stationary part as in other motors.
• The stationary stator of the motor is supplied with an AC power supply which is single phase.
• Stator is a cylindrical frame having slots.
• Inside the stator frame, cylindrical core of rotor is placed with a little air gap in between them.
• The purpose of making slots is to carry winding circuit.
• The winding circuitry of stator is called stator winding which in the case of this particular motor is single phase.

You may also like to read:

• Squirrel Cage Induction Motor.
• Wound Rotor Induction Motor.
• 3 Phase Induction Motor.
• Introduction to Synchronous Motor.

Rotor of Single Phase Induction Motor

• The second basic part of motor is the rotor.
• As in all other motors, the rotor is the rotating part.
• Rotor is cylindrical in shape and it is connected to the output shaft of the motor.
• In other words, this is the part which supplies rotation at the output. Load is connected to the shaft of rotor.
• Rotor of a single phase induction motor is similar in construction with a squirrel cage 3 phase induction motor. I have explained its construction in my article on 3 phase induction motor.
• Rotor has slots on all over its surface to carry conductors that are copper or aluminum bars.
• These conductor bars are short circuited with each other by two end rings. One end ring is on each side of rotor.
• Just like rotor of a squirrel cage 3 phase induction motor, it has no slip ring and brush assembly.
• That was all about basic structure of stator and rotor, now I am moving towards next section of this article.

Working of Single Phase Induction Motor

The working principle of a single phase induction motor is based on Faraday’s law of electromagnetic induction. AC supply is given to stator windings which is single phase, the current flowing through the winding will produce a magnetic field which is called stator magnetic field. The flux lines of this magnetic field will cross the conductors of rotor. As the flux is changing due to changing magnetic field of AC supply with time, an emf and current will be induced in the rotor. The induced current will give rise to another magnetic field which is called rotor magnetic field.   A single phase induction motor differs in operation from a 3 phase induction motor in the sense that this motor cannot generate a rotating magnetic field. Instead of a rotating magnetic field, it produces a magnetic field which pulsates due to AC oscillations between 0 and 180 degrees. In other words, the magnetic field does not rotates but reverses 180 degrees. The interaction of the two magnetic fields or magnetic fluxes, one from stator and second from rotor will produce torque.

Advantages of Single Phase Induction Motor

In this section, I am highlighting some of the advantages of a single phase induction motor which are as under.

• A single phase induction motor is more economical where less power is required.
• Such motor is simple in construction because of absence of slip rings and brushes.
• Because of simple construction, it is very easy to maintain and repair.
• This motor is cheap in cost.
• Also, single phase induction motors are reliable and robust.

Starting Problem of a Single Phase Induction Motor

The initial torque or starting torque of a single phase induction motor is very low so this motor cannot take a self start. For 3 phase induction motor the starting torque is high so it can start on its own. Now to overcome this starting problem, capacitor can be used to build the starting torque. This capacitor creates a phase difference between the flux of rotor and flux of stator. The capacitor is used with a starting winding which is switched off once the motor is started.

Comparison of Single Phase and 3 Phase Induction Motors

In this segment of my article, I am going to give a little comparison of single phase and 3 phase induction motors so you can get an idea which one is best for your application. Both are compared on the basis of their features, construction, supply and uses.

• The output produced by a single phase induction motor is about half as produced by 3 phase induction motor.
• A single phase induction motor is used where less power is required as compared to 3 phase induction motor.
• The efficiency and power factor is also low in case of single phase induction motor.
• Single phase motors are simple and cheaper for small rating as compared to 3 phase induction motors.
• Starting torque is low in single phase motor as compared to 3 phase induction motor.
• Single phase induction motors are used for domestic applications while 3 phase induction motors are used in industrial applications.
• Maintenance of a single phase motor is very easy in contrast with 3 phase induction motor.
• Another important point is the construction. It’s easy to construct a single phase induction motor as compared to 3 phase induction motor.
• Single phase induction motor is reliable and economical if compared to 3 phase induction motor.
• 3 phase induction motor is self starting while single phase induction motor is not a self starting motor.

Introduction to Induction Motor

Hi fellows! Hoping everyone is fine and doing great. Today, I am going to give you an Introduction to Induction Motors, the term which is very common and familiar but still many of us do not know it’s working and difference from other motors. Induction Motor is an AC electric motor, having a stator and a rotor just like other motors, but the working principle is a little different which would be discussed further. There are two types of Induction Motors, one is named as Single Phase Induction Motor, while the second one is named as 3 Phase Induction Motor.

An Induction motor is also called asynchronous motor, because the speed of rotation of its rotor is less than stator. In other words, it does not run at its synchronous speed. Before going into the details of the working principal of induction motor, I wanna first summarize the basic concepts of Rotor and Stator:

Rotor

• Rotor is the rotating part of the induction motor, which is actually the shaft of the motor.
• Rotor of an Induction motor is a laminated cylindrical core.
• Moreover this laminated cylindrical core has slots that carry aluminum or copper conductors, which are joined at ends.
• So, let's now have a look at the stator of the induction motor.

Stator

• In the previous section, we have discussed the rotor details, now I am gonna throw some light on stator.
• Unlike rotor, stator is the stationary part of the induction motor.
• While rotor is a small cylindrical core which rotates in the outer cylindrical frame of the motor. This outer cylindrical frame is named as stator.
• Stator has slots to carry the winding circuit which is supplied by an AC power.

Both stator and rotor are made up of an electric circuit to carry current and a magnetic circuit to carry magnetic flux. You may also like to read:

• Squirrel Cage Induction Motor.
• Wound Rotor Induction Motor.

Working of Induction Motor

The working of an Induction Motor can be summarized as, “the stator winding produces magnetic field and due to electromagnetic induction a current is induced in rotor which produces torque”. No electrical connection exists between rotor and stator which differentiates it from other motors (DC, Synchronous), as it works on Faraday’s law of Electromagnetic Induction. The AC power supplied to the stator creates a magnetic field which is changing over time due to AC oscillations. This changing magnetic field produces changing magnetic flux that induces a current in rotor windings in accordance with Faraday's law. This current will generate a magnetic field to oppose the stator magnetic field in accordance with Lenz’s law. To oppose this change, the rotor will start rotating in the direction of changing magnetic field of the stator. Relative speed of the stator’s magnetic field and rotor is the driving factor. Therefore, the speed of rotor is always maintained less to keep it moving. Let’s take a look on some parameters of an Induction Motor like poles, synchronous speed, slip and power factor.

Poles

• Number of poles of an induction motor is denoted by “p”.
• A single phase AC machine has 2 poles of opposite polarity set at 180 degree apart.
• A simplest 3 phase machine has 6 poles which are set at 60 degree apart.

Synchronous Speed

• It is the speed of rotation of stator’s magnetic field denoted by “n_s”.
• n_s= 2f/p

Where, f = frequency of AC supply p = no. of poles

Slip

• Slip is the difference between stator's magnetic field and rotor's mechanical speed of the induction motor.
• We can also say that its the difference between synchronous speed and operating speed. expressed as a ratio.
• s=(n_s-n_r)/n_s

Power Factor

• The power factor of a motor is the ratio of real power to the apparent power.
• At full load power factor of an induction motor ranges from 0.85 to 0.90 and at no load it is approx. 0.12.

Types of Induction Motors

Now lets just take a brief look on types of induction motor. Single phase and three phase are the two types of an AC Induction Motor. Single phase motors are used for smaller loads while 3 phase motors are used in high load applications.

According to the type of rotor, an induction motor is divided into two types; squirrel cage and slip ring /wound type motor. The most commonly used is the squirrel cage induction motor. Concluding, Advantage of Induction Motor is its simple operation, reliability and low cost. It is used in a number of applications in home appliances and commercial uses such as pumps, compressors, fans, mixers, conveyors, crushers, machine tools, cranes, etc.

Line Following Robot using Arduino

Hello everyone, I hope you all are fine and having fun with your lives. Today, I am going to share a very basic project named as Line Following Robot using Arduino. I have designed a three wheeler robot and have placed IR sensors beneath it to detect the black line and then I have made it move over this Black Line.

This Line Following Robot is not doing any extra feature i.e. turning or rotating back. It will just simply move in the straight line. I have also posted a short video at the botton of this tutorials which will give you better idea of how this robot moves. You should first read this tutorial and design the basic robot and once you are successful in designing the basic Line Following Robot then you should have a look at my recent Project Line following Robotic Waiter in which I have designed a Robotic waiter which follows the line and also take turns on different tables. So, let's get started with Line Following Robot using Arduino.

Line Following Robot using Arduino

• First of all I have designed the Mechanical model of the robot, which has three wheels on it.
• Its a triangular method in which the motors were attached to the front two wheels and the back wheel is a caster wheel, which is present in the middle of the robot.

• Here's the image of front wheel coupled with the DC Gear Motor:

• Now let's have a look at the rear caster wheels, shown in below image:

• Finally, I have used Acrylic as the body of the robot.
• Here's the assembled version of our Line Following Robot:

• Now that we have the mechanical design of our robot and we have assembled it completely.
• So, now comes the electronics part where we are gonna place the DC Motor Driver Circuits and will also place the IR sensors.
• I have used Arduino board for programming of this Line following Robot.
• First of all, I have designed the 2 relay baord for DC motors.
• Its circuit diagram is shown in below figure:

• We also need a voltage divider circuit because we need such a power supply from which we can get 5V, while our source battery is of 12V.
• So, in order to do that I have used 7805 Regulator IC and have designed a simple circuit as shown in below figure:

• Now placing all the components over the Line following Robot, it looked like something as shown in below figure:

• Here's the Arduino code which you need to upload in your Arduino board:

#define motorL1 8
#define motorL2 9
#define motorR1 10
#define motorR2 11

#define PwmLeft 5
#define PwmRight 6

#define SensorR 2
#define SensorL 3
#define Sensor3 A0
#define Sensor4 A1

#define TableA A4
#define TableB A2
#define TableC A5
#define TableD A3

int OriginalSpeed = 200;
int TableCount = 0;
int TableCheck = 0;
int RFCheck = 10;

void setup() 
{
  Serial.begin (9600);
 
  pinMode(motorR1, OUTPUT);
  pinMode(motorR2, OUTPUT);
  pinMode(motorL1, OUTPUT);
  pinMode(motorL2, OUTPUT);
  
  pinMode(PwmLeft, OUTPUT);
  pinMode(PwmRight, OUTPUT);
  
  pinMode(SensorL, INPUT);
  pinMode(SensorR, INPUT);
  pinMode(Sensor3, INPUT);
  pinMode(Sensor4, INPUT);
  
  pinMode(TableA, INPUT);
  pinMode(TableB, INPUT);
  pinMode(TableC, INPUT);
  pinMode(TableD, INPUT);
  
  MotorsStop();
  
  analogWrite(PwmLeft, 0); 
  analogWrite(PwmRight, 0);
  delay(2000); 
 // Serial.println("fghfg");
  
}

void loop() {
  MotorsForward();
  PIDController();
}

void MotorsBackward()
{
    digitalWrite(motorL1, HIGH);
    digitalWrite(motorL2, LOW);
    digitalWrite(motorR1, HIGH);
    digitalWrite(motorR2, LOW);
}

void MotorsForward()
{
    digitalWrite(motorL1, LOW);
    digitalWrite(motorL2, HIGH);
    digitalWrite(motorR1, LOW);
    digitalWrite(motorR2, HIGH);
}

void MotorsStop()
{
    digitalWrite(motorL1, HIGH);
    digitalWrite(motorL2, HIGH);
    digitalWrite(motorR1, HIGH);
    digitalWrite(motorR2, HIGH);
}

void MotorsLeft()
{
    analogWrite(PwmLeft, 0); 
  analogWrite(PwmRight, 0);
    digitalWrite(motorR1, HIGH);
    digitalWrite(motorR2, HIGH);
    digitalWrite(motorL1, LOW);
    digitalWrite(motorL2, HIGH);
}

void MotorsRight()
{
      analogWrite(PwmLeft, 0); 
  analogWrite(PwmRight, 0);
    digitalWrite(motorR1, LOW);
    digitalWrite(motorR2, HIGH);
    digitalWrite(motorL1, HIGH);
    digitalWrite(motorL2, HIGH);
}

void Motors180()
{
    analogWrite(PwmLeft, 0); 
    analogWrite(PwmRight, 0);
    digitalWrite(motorL1, HIGH);
    digitalWrite(motorL2, LOW);
    digitalWrite(motorR1, LOW);
    digitalWrite(motorR2, HIGH);
}

void PIDController()
{
  if(digitalRead(SensorL) == HIGH){analogWrite(PwmRight, 250);analogWrite(PwmLeft, 0);}
  if(digitalRead(SensorR) == HIGH){analogWrite(PwmLeft, 250);analogWrite(PwmRight,0);}
  if((digitalRead(SensorL) == LOW) && (digitalRead(SensorR) == LOW)){analogWrite(PwmRight, 0);analogWrite(PwmLeft, 0);}
}

• Now that's all, here's the video for Line Following Robot using Arduino which will give you better idea:

That's all for today. I hope you have enjoyed this Line Following Robot using Arduino and are gonna use it in your projects. feel free to ask in comments, if you got into any trouble. Thanks for reading. Take care !!! :)

Automatic Street Light Project in Proteus

Hello everyone, I hope you all are fine and having fun with your lives. Today, I am going to share a semester project which is named as Automatic Street Light Project. I have designed this project in Proteus ISIS and the simulation is also given below for download. Btw this was my first project during my engineering course. :D I had really enjoyed while working on this project as I was new to electronics then.

This project is about Automatic Street Light. You must have examined on your streets that the street lights turn ON at night while they turn OFF in the day. When I was a child then I think that someone turns ON the switch in the day and then turns it OFF at night but that's really not the case. :P

In fact, these lights are automatic and have a sensor in them which is known as LDR sensor. This sensor is used to detect the light intensity so if there's sun light in the surroundings then it simply turn OFF the street light and if there's no sun light then it turns ON the street light and that's how Automatic Street Light works. I have designed its simulation in Proteus ISIS software which you can download below. So, let's get started with Automatic Street Light Project in Proteus ISIS.

Note:

• You should also have a look at How to use LDR sensor in Proteus ISIS, if you wanna work on this project.

Automatic Street Light Project in Proteus ISIS

• You can download the working simulation of Automatic Street Light Project designed in Proteus ISIS by clicking the below button:

Download Proteus Simulation

• You can download the Proteus simulation by clicking the above button but I would recommend you to design it on your own so that you get maximum knowledge out of it.
• So, let's design it on our own. :)
• First of all, design a simple circuit as shown in below figure:

• You can see in the above figure that I have designed two circuits. Both of these circuits are exactly same but they have different LDR sensors.
• Proteus has two LDR sensors in its database that's why I have designed two circuit diagrams and have used both of them.
• Moreover, I have used LM324 IC in it which is getting the input from the LDR sensor at its negative pole and the LED is attached at its output.
• LDR is a Light Dependent Resistance which gives output when it detects light.
• The output of LDR is analog and it depends on the light intensity.
• If the light intensity is HIGH then LDR value will be HIGH if its LOW then value will be LOW.
• That's why I have placed a variable resistance which is used for setting the threshold value for LDR.
• Rite now when there is full light only then the LED will go HIGH otherwise it will remain LOW.
• So, let's now simulate this simulation of Automatic Street Light and have a look at the results:

• You can see in the above figure that in the OFF state the LED is OFF when LDR is not detecting light.
• Now in the ON state, when LDR detected the Light then the LED goes ON automatically.
• You must be wondering that its working on opposite logic i.e. when there's light then the Light goes HIGH and when there's no light then the Light goes LOW.
• Moreover, the output is just of 5V but the street lights are of normally 220V AC or 12V DC.
• So, let's add a simple Relay in front of this circuit so that we can add some lamp as shown in below figure:

• Now let's have a look at the OFF state of this Automatic Street Light Project, shown in below figure:

• You can see in the above figure that the LDR is detecting the light but the Lamp is OFF, so its like a day time. There's light and that's why street light is OFF.
• Now, let's have a look at its ON state in the below figure:

• Now you can see the LDR is not detecting any Light which means its a night time and that's why our lamp is ON.
• The below video will give you a better idea of How it works:

So, that's all for today. I hope you have enjoyed this Automatic Street Light Project in Proteus ISIS. Will meet you guys in next tutorial. Till then take care and have fun !!! :)

Capacitive Touch Sensor Library for Proteus

Hello everyone, I hope you all are fine and having fun with your lives. Today, I am going to share a new Capacitive Touch Sensor Library for Proteus, which is designed for the first time by our team. :) Capacitive Touch Sensor is used to sense the presence of a human finger on the sensor.

We all know that human carries a charge, which is used by these touch sensors. These sensors are available these days online and you can easily buy them. I have designed its Proteus Library which I am presenting today for free to our readers. I hope you guys are going to enjoy working on it. :) So, let's get started with Capacitive Touch Sensor Library for Proteus:

Capacitive Touch Sensor Library for Proteus

• First of all, click on the below button to download Capacitive Touch Sensor Library for Proteus:

Capacitive Touch Sensor Library for Proteus

• When you download the files, you will get three files, named as:
• TouchSensorTEP.LIB
• TouchSensorTEP.IDX
• TouchSensorTEP.HEX
• Place all these three files in the library folder of your Proteus software.

Note:

• If you are using Proteus 7 Professional, then the library folder link will be something like this: C:Program Files (x86)Labcenter ElectronicsProteus 7 ProfessionalLIBRARY
• If you are using Proteus 8 Professional, then the library folder link will be something like this: C:ProgramDataLabcenter ElectronicsProteus 8 ProfessionalDataLIBRARY

• Now restart your Proteus software if you have already opened it or start it if it's not open. :P
• In the components search box, search for Touch Sensor and place it in your workspace.
• If everything goes fine, then you will get a touch sensor as shown in below figure:

• Now, the next thing you need to do is to add the functionality to it.
• So, double-click this vibration sensor and in the Program file section browse for the TouchSensorTEP.HEX file which we have placed in the library folder of Proteus.
• Upload it in the Program file section and now you are ready to use this sensor.
• Let's test this sensor out.
• So, design a simple circuit diagram as shown in the below figure:

• Because it's a simulation and we can't actually touch the sensor so that's why I have placed a TestPin.
• When this TestPin is HIGH, it means that your sensor is sensing the touch and when it's LOW, it means that there's no touch.
• So, now let's run this simulation and see what happens:

• So, that's how this Capacitive Touch Sensor Library for Proteus works.
• When you make the TestPin Low then it means there's no touch detected by the sensor and it will give LOW at the output.
• Similarly when TestPin goes HIHG then it means there's a touch and the sensor will give HIGH at the OUT Pin.
• Here's a video in which I have explained in detail How to use this Capacitive Touch Sensor Library for Proteus.

That's all for today. I hope you guys are gonna enjoy this Capacitive Touch Sensor Library for Proteus. Will meet you guys in the next tutorial. Till then take care and have fun !!! :)

Getting Started with Cayenne - Arduino

Hello friends, I hope you all are fine and having fun with your lives. Today, I am going to share a new and very exciting service with you guys which is named as myDevices Cayenne, we will have a look at getting started with Cayenne. Its really an awesome platform for students and hobbyist who wants to work on embedded systems but are afraid of programming codes.

Cayenne is an online project building platform using drag and drop. Currently it supports Arduino and Raspberry Pi. In simple words, you can design any of your Arduino or Raspberry Pi project simply by drag and drop different components. You don't need to write any code, you just need to place your blocks and upload it to your Arduino board. Its also known as the Graphical coding.

I came to know about Cayenne a few days ago and I have really enjoyed working on it so I thought to share it with you guys so that you can also get benefit from it. In today's tutorial, I am just gonna give an overview of Cayenne and we will design a simple Arduino LED project on it. In the coming tutorials I will share different projects on Cayenne, which will help you guys in your projects. Moreover, first we will cover the Arduino Project on Cayenne and later we will work on Raspberry Pi as well. So, let's have a look at Getting Started with Cayenne.

Getting Started with Cayenne

• First of all, what you need to do is to open this myDevices Cayenne Website.
• Now on this myDevices Cayenne Website you have a to create a free account so click on the Green Button which says Get Started for Free.

• So, fill out the form on the Registration page and then it will ask you which one you want to use as shown in below figure:

• Now as we are gonna work on Arduino so I will select Arduino among them.
• You must have the Arduino IDE installed on your computer and you should also install the Cayenne Library for Arduino.

Note:

• When I first started working on Cayenne, I had an older version of Arduino software and when I compiled the code then it generated errors, so I updated my Arduino software and it worked fine.
• So, you just make sure to have the latest Arduino IDE.

• Next thing you need is the Arduino Ethernet or Arduino Wifi Shield, which will be used for uploading the code to Arduino board from Cayenne website.
• So, now plug your Ethernet or Wifi shield on the Arduino board.
• I have plugged Arduino Wifi shield with Arduino UNO.
• So, now once you selected the Arduino then on the nex page you will get some instructions, which I have already disscused.
• Now you should plug your Arduino board with your computer and click Next.
• In this step you need to select your device as shown in below figure:

• In the above figure, you can see first of all, I have selected the Arduino UNO shield becasue I want to upload the code in this shield and then I have selected the Wifi Shield using which the code will be uploaded.
• Now when you click on the Sketch button you will get a small sketch which you need to upload in your Arduino board.
• This is the only code which you need to upload, this code is acting as a bridge between Arduino and Cayenne.
• Once you uploaded that code then Cayenne will automatically detect your board, you just need to wait.
• As soon as your board is detected, you will be redirected to your Dashboard, where you can design your first project as shown in below figure. :)

Arduino LED Blinking Project in Cayenne

• Now Click on the Create new Project button and give it a name, I have given it Arduino LED and click OK.
• The new project will be created, now we need to add the LED Control in it.
• So, in order to do so you need to click on the Add new button and then Device/ Widget as shown in below figure:

• You can see in the above figure, that all the devices are now visible.
• As we are working on the LED, so you need to click the Light icon, which is among Actuators.
• When you click it you will get something as shown in below figure:

• So, I have selected the Light switch and in its properties, I have selected the D8 which is 8th digital Pin of Arduino.
• Now click on the Add Actuator button and you are done.
• You first LED Blinking Project is done on Cayenne and it will look something as shown in below figure:

• So, now when you click this light switch your LED on pin 8 will go ON and if you click it again then it will go OFF.
• I have plugged an LED on Pin # 8 on my hardware.
• In the below video, I have explained this Arduino LED project in more detail, so must watch it:

I hope you guys have enjoyed today's tutorial and are gonna like this Cayenne online Platform. I will post more tutorial on it in which I will interface all these devices with Arduino. So, stay tuned and have fun !!! :)