Showing posts with label Electrical Machine. Show all posts
Showing posts with label Electrical Machine. Show all posts

Sunday, December 30, 2018

December 30, 2018

Motor Starter, Applications and Advantages

If you an electrical engineering student then you must hear about the motor starter. As an electrical engineer, you should know all types of starter and their applications, advantages.

What is Motor Starter

An electrical motor starter is a device or can be called a circuit which is to be connected in series with the motor to reduce the starting current and maintain the starting speed of the motor and also to protect the motor from overload, short circuit faults.
An electrical motor starter can be used alone or with the Contactor, circuit breaker according to requirement.
We also can say a motor starter is a device which is used to start and stop a motor safely.
The main principle of a motor starter is that it reduces the terminal voltage and current of the motor during starting time.

DC Motor Starter Types, Applications and Advantages

DC Motor Starter, types of motor starter

The starter is used for DC motors is called DC Motor Starter. To safely start and stop the DC Motors DC Motor starters are used. DC Motor starter does not only start and stop the motor safely they also protect the motor from over voltage and short circuit faults. DC motor starters very simple in construction and they are cheaper than AC Motor Starter.
Why we need a Starter for starting of DC Motor
In DC motor there is no principle of induction exists. Back EMF is very important for running of a DC Motor. As the polarity of back emf is opposite to the supply voltage, therefore, the back emf can control the armature current.
When the motor is in off condition there is no back emf in the armature winding. And we know that the resistance of the armature winding also very low. Now if we connect the motor to the full supply voltage a huge amount of current will flow through the armature winding. It can be shown by the equation
Ia=(V-Eb)/Ra
You can see the back emf (Eb) is Zero and the armature resistance (Ra) is also very low so the value of armature current (Ia) will be very high.
This huge amount of armature current may causes,
  1. Burning of the armature winding
  2. Damage the commutator and brushes
  3. A large voltage fluctuation in supply voltage which can damage other equipment.
So for these reasons to reduce the starting current Starter is used with DC Motors.

Types DC Motor Starter

There are three types of DC Motor Starter,
  1. Two-point Starter
  2. Three-point Starter
  3. Four-point Starter

Applications of Two-point Starter

  1. Two-point starters are used with DC series motors.
  2. Two-point starters are used in railway to start or stop the rail.
  3. Two-point starters are used in cranes.

Advantages of Two-point Starter

  1. It protects the motor from drawing high starting current.
  2. It can give protection against overload and short circuit faults.
  3. It automatically gets off when the power supply is off.

Applications of Three-point Starter

  1. The three-point starter is used with DC Shunt motors
  2. Three-point starters are used in lathe factories
  3. Three-point starters are used in spinning mills

Advantages of Three-point Starter

  1. Three-point starter gives the protection to the motor from overload and short circuit faults.
  2. The three-point starter helps to speed control of the motor by adding some extra equipment.

Disadvantages of Three-point starter

The main disadvantage of the three-point starter is that it is not suitable for variable speed motors.

Application of Four-point Starter

  1. The four-point starter is used with mainly DC compound motors but it can be used with DC shunt motors.
  2. Four-point starters are used in press industries.
  3. Four-point starters are used in rolling mills

Advantages of Four-point Starter

  1. The four-point starter is suitable for variable speed motors.

AC Motor Starter Types, Applications and Advantages

AC Motor Starter, types of motor starter



The starter used for AC motors is called AC Motor Starter. Like DC motor AC motor also need the starter for safely starting. Induction motors are widely used in any industry. Induction motor need starter for safely staring. So we will discuss the starter of induction motors.

Why we need Starter for starting of Induction Motor

We know that the Induction Motor is acting as a transformer with the secondary winding short-circuited during off condition.

We know that, I1N1=I2N2

This equation is the same for the transformer and the Induction motor at standstill condition

Where I1= primary winding current or stator winding current

           N1 = no. of turns in primary winding or stator winding
           I2 = Secondary winding current or rotor winding current
           N2= no. of turns in secondary winding or rotor winding

So at standstill condition of the motor if we connect the motor directly to the full supply voltage a high-value emf will be induced in the rotor of the induction motor for the transformer action. This high-value emf will cause to flow a high current(I2) in the rotor winding. A huge amount of current also will be flow in the stator winding to balance the equation, I1N1=I2N2

This high current in stator winding may,

  1. Damage the stator winding.
  2. Create a large fluctuation in supply voltage which may damage others equipment connected in the same line.
For these reasons, to reduce the magnitude of supply voltage and current at starting period Starter is used with the Induction motor.

Types of AC Motor Starter

  1. Direct-on-line Starter or DOL Starter
  2. Stator resistance starter
  3. Autotransformer Starter
  4. Star-Delta Starter
  5. Rotor Resistance Starter

Applications of Direct-on-line Starter or DOL Starter

  1. DOL starters are used with up to 7.5 KW Induction Motors.
  2. DOL starter acts as normally ON/OFF switch so it is used where frequently start and stop of the motor is required.
  3. DOL starters are used in conveyor belt and compressor.

Advantages of Direct-on-line Starter or DOL Starter

  1. It is very simple in construction.
  2. It is cheaper than other starters
  3. It can give overload and short-circuit protection.

Disadvantages of Direct-on-line Starter or DOL Starter

  1. It can not be used with more than 7.5 kW motors.
  2. It can not reduce the magnitude of starting current of the motor acts only normal ON/OFF switch.

Applications of Stator Resistance Starter

  1. This types of starter are suitable for more than 7.5 KW rating motors.

Advantages of Stator Resistance Starter

  1. It is very simple in construction.
  2. It reduces the terminal voltage of the motor during the starting time hence the starting current also decreases.
  3. It is also a low-cost starter.

Disadvantages of Stator Resistance Starter

  1. It lowers the starting torque of the motor.
  2. It increases the accelerating time of the motor
  3. A huge amount of power loss in by the starting resistance.

Advantages of Auto-Transformer Starter

  1. Simple operation
  2. Very low power loss as it has no resistance
  3. Easy to control

Disadvantages of Auto-Transformer Starter

  1.  It lowers the starting torque of the motor
  2. There is a chance of sparking.

Applications of Star-Delta Starter

  1. It used in heavy industries for starting high KW motors.

Advantages of Star-Delta Starter

  1. Star-delta starter can be controlled automatically by using electronic circuits
  2. Low power loss
  3. Smooth operation
  4. Starting current is reduced to one-third of full load current

Disadvantages of Star-Delta Starter

  1. Low starting torque
  2. Six terminals motor required.

Application of Rotor Resistance starter

  1. These starters are used with slip-ring induction motors.

Advantages of Rotor Resistance starter

  1. It can not decrease starting torque.
  2. Smooth speed control is possible.

Solid State Starter or Soft Starter

Nowadays Solid State Starters are widely used instead of the magnetic starter. in industries. Solid state starter has no moving elements. These Starters uses the Silicon Controlled Rectifier for their operation.

Advantages of Solid State Starter or Soft Starter

  1. These starters eliminate the power distribution issues in industries.
  2. These starters can handle multiple motors at a time.
  3. These starters decrease the acceleration time of the motor
  4. Very low power loss.

Applications of Solid State Starter or Soft Starter

  1. These starters are used in industry for the operation of Conveyor belt motors.
  2. It used with blowers to increase the accel time.
  3. These Starters are used with pumps also.
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December 30, 2018

Difference between Generator and Alternator

Difference Between Generator and Alternator

Difference between generator and alternator Full explanation, generator vs alternator

Generator and Alternator both are very important terms in electrical engineering. Most of the Students have confused about the difference between generator and alternator. Some of the students think that they are the same and some of the students think that they are different. In this article, I will clear all doubts about the Difference between Generator and Alternator.
The Alternator and Generator both convert mechanical energy into electrical energy. So what is the difference between generator and alternator? The main difference between the alternator and generator is in the generator the magnet (either the permanent magnet or electromagnet) or field system is stationary and the armature is rotating but in case of the alternator the armature is stationary and field is rotating.The other important difference between generator and alternator are below.

Difference between generator and alternator Full explanation, generator vs alternator

Key Difference between Generator and Alternator

  1. The Generator has Armature as rotating part and has the main field as stationary part. On the other hand, the Alternator has the main field as a rotating part and has the armature as stationary part.
  2. The generator may be two types AC or DC. There are both types are available. But the alternator only can produce Alternating current that is why it is called Alternator.
  3. The generator always used for small amount of power generation and the RPM of generator always less than the alternator. Alternator mainly used for a large amount of power generation and also used for small amount of power generation. The alternator has a large RPM rating than the generator.
  4. We know that in DC generator the induced emf in the armature winding is alternating in nature and it causes to produce alternating current so to convert alternating into direct current commutator is used in DC Generator. On the other hand, Alternator has not any commutator mechanism.
  5. Among the same rating of generator and alternator, the generator always has less efficiency than the alternator for its brush, commutator, and other reasons. But alternator has more efficiency than the generator.
  6. Among the same rating of generator and alternator, the generator is heavier than the alternator for its commutator and other arrangements. On the other hand, as the alternator has no commutator arrangement so lighter than the generator.
  7. We know that DC has polarity positive and negative. So polarization must be taken during installation of A DC generator. For AC generator it does not need. During installation of the alternator also polarization does not need.
  8. As I told you previously that generators are used for only low power generation purposes but the alternators are used for low power generation as well as high power generation. 

So the main difference between generator and alternator is the constructional difference and power generation capacity. You can write the above differences in your exam.
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Monday, December 17, 2018

December 17, 2018

Speed Control of DC Shunt Motor - Easy Methods.

Speed Control of DC Shunt Motor.

speed control of dc shunt motor, Speed Control of DC Shunt Motor by Field Current Control Method, Speed Control of DC Shunt Motor by Armature Voltage Control Method



The electrical machine is one of the most important subject in Electrical Engineering. If you are a student of Electrical Engineering then you should know that "Speed Control of DC Shunt Motor". Of course, before going to know Speed control of DC Shunt Motor we will learn what is DC Shunt Motor. So let's know What is DC Shunt Motor and Speed Control of DC Shunt Motor.


What is DC Shunt Motor?

DC Shunt Motor is a DC Motor whose field coil is connected in parallel with the Armature coil. As the Field coil is connected in parallel(or as a shunt) with the armature coil that is why it called DC Shunt Motor. 


Speed Control of DC Shunt Motor Formulas:

Are you know what is speed control. Speed control means a change in rotation of the motor by us. Now there is a question that how speed control is possible of a DC Shunt Motor. 
At first, let's see the EMF Equation of the DC Motor;

E= (P�NZ)/60A

Here, 
E= EMF
N= Speed
�= Flux per pole
Z= No. of Conductors
A= Parallel path

 As the P, Z, A,60 are constant so we can write,


 E=N�K               where K=PZ/60A

So the speed equation is N=E/K�


According to the above equation, the speed of the DC motor can be changed by changing the Flux and Terminal voltage of the Armature.
Flux can be changed by changing the field current. So we will discuss the two methods of  Speed Control of DC Shunt Motor-
  1. Field Current Control Method
  2. Armature Voltage Control Method


Speed Control of DC Shunt Motor by Field Current Control Method:

Speed control of DC Shunt Motor by Field Current Control Method is Very Easy. From the equation, we know that if we decrease the current in the field coil speed will be increased and vice-versa.

Apparatus Required:

  1. Rheostat.
  2. Ammeter.
  3. Voltmeter.

 Procedure: 
  1. Find the terminals A1, A2, F1, F2 in terminal box of the motor.
  2. Find the terminals L, LC(or N), A, F in the four-point starter.
  3. Connect the DC power supply to the L and LC terminals of the starter.
  4. Connect the A2, F2, LC terminals together.
  5. Connect the A1 terminal of the motor to the A terminal of the starter.
  6. Connect the one terminal of the rheostat to the F terminal of the starter and another terminal to the F1 terminal of the motor.
  7. If you measure the current and voltage then you can use ammeters and voltmeter.
  8. For better understanding see the Circuit diagram carefully.
  9. Now move the slider of the rheostat to get your desired speed.


Circuit diagram for Speed Control of DC Shunt Motor by Field Current Control Method:

click on the image to enlarge


Speed Control of DC Shunt Motor, Circuit diagram for Speed Control of DC Shunt Motor by Field Current Control Method, Speed Control of DC shunt motor circuit diagram


Note: By using this method you can increase the speed of the motor above the rated speed.


Speed Control of DC Shunt Motor by Armature Voltage Control Method:

Generally, as the supply voltage is constant the armature voltage also constant. If we decrease the voltage across the armature by increasing a variable resistance in series with the armature the back emf will be decreased hence the speed will be decreased.


 Apparatus Required:
  1. Rheostat.
  2. Ammeter.
  3. Voltmeter.
Procedure:
  1. Find the terminals A1, A2, F1, F2 in terminal box of the motor.
  2. Find the terminals L, LC(or N), A, F in the four-point starter.
  3. Connect the DC power supply to the L and LC terminals of the starter.
  4. Connect the A2, F2, LC terminals together.
  5. Connect the F1 terminal of the motor to the F terminal of the starter.
  6. Connect the one terminal of the rheostat to the A terminal of the starter and another terminal to the A1 terminal of the motor.
  7. If you measure the current and voltage then you can use ammeters and voltmeter.
  8. For better understanding see the Circuit diagram carefully.
  9. Now move the slider of the rheostat to get your desired speed.



Circuit diagram for Speed Control of DC Shunt Motor by Armature Voltage Control Method:

click on the image to enlarge


Speed Control of DC Shunt Motor, Circuit diagram for Speed Control of DC Shunt Motor by Armature Voltage Control Method, Speed Control of DC shunt motor circuit diagram
Note: By using this method you can Decrease the speed of the motor below the rated speed.


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Friday, December 14, 2018

December 14, 2018

Why Capacitor is used in Single phase Induction Motor?Full Explanation.

Why Capacitor is used in Single phase Induction Motor?


Nowadays single phase motors are widely used in our house, office and other areas. Single phase motor becomes very popular as it is low cost. 

 There are three types of Single Phase motor

  1. Induction motors
  2. Commutator motors
  3. Synchronous motors

You may notice that every single phase induction motor (except Shaded pole Induction Motor) need one or more capacitor. So today we are going to know Why Capacitor is used in Single phase Induction Motor? or Why Capacitor is used in Fan?

 Why Capacitor is used in Single phase Induction Motor: The answer is that as the single phase induction motor is not self starting so the capacitor is used to make single phase induction motor self starting.


Why Single Phase Induction Motor is not self starting?


The Single Phase Induction Motor is not self starting because if we give single phase AC supply to the stator winding of the single phase induction motor the stator winding produces alternating flux and for the transformer action, an alternating emf is produced on the rotor winding which causes to flow alternating current in the rotor winding. 

 So an alternating flux also produced in the rotor winding which tried to oppose the stator emf. Therefore no torque will develop in the rotor. So when we give single phase AC supply the motor not start rotating it will vibrate. So for this reason capacitor is used in Ceiling Fan as well as any single phase induction motor.


How to start a single phase induction motor?


After giving the single phase AC supply if we push the rotor by hand or by another means in either direction, it will pick up the speed and continue to rotate in the same direction developing operating torque.


How the Capacitor make the single phase induction motor self starting?


To make the single phase induction motor self starting we need to add an extra winding which is called starting winding. And the winding will be connected in series with a capacitor. By using a capacitor of proper value, the starting winding current can be made to lead the main winding current by 90o. That means the capacitor creates a phase difference between the two windings and the starting winding push the rotor to start rotating.

Single Phase motor connection with Capacitor Diagram:


The below circuit diagram is of the Permanent Capacitor single phase Induction motor. This is also the circuit diagram of a ceiling fan.


Why Capacitor is used in Single phase Induction Motor, Single Phase motor connection with Capacitor Diagram, Why Single Phase Induction Motor is not self starting



What type of motor used in Ceiling Fan?

Single phase squirrel cage capacitor start capacitor run induction motor used in Ceiling Fan.


How to connect the capacitor with the ceiling fan?


At first measure the resistance of each winding. The starting winding has less resistance than running winding. Then connect the capacitor according to the above circuit diagram.

Which type of Capacitor used in Ceiling Fan?

Mainly Oil filled capacitor used in ceiling Fan. Nowadays, the dry capacitor with high insulation used in the ceiling fan. 



How to change the direction of rotation of single phase induction motor?

To change the direction of rotation of single phase induction motor reverse the connection of any one winding either starting winding or running winding.

Which type of single phase induction motor can run without capacitor?

The shaded pole induction motor can run without the capacitor.

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Saturday, December 1, 2018

December 01, 2018

Three Reasons Why Transformer Ratings in KVA.

The transformer is the most important electrical machine which transfers electrical power. If you do not know how a Transformer works then you can read our article Working of a Simple transformer.
Today we are going to know the Three Reasons Why Transformer Ratings in KVA, not KW or KVAR.




Three Reasons Why Transformer Ratings in KVA, Why Transformer Ratings in KVA, not KW.




 The three reasons why transformer ratings in KVA given below,


Why Transformer Ratings in KVA.


(1) KVA= KV(killo Volt) * A(ampere)
KW= KV(killo Volt) * A(ampere) * Power factor

We already know that Power factor only depends on the type of Loads like,
  • Inductive Load - Lagging Power factor
  • Capacitive Load - Leading Power Factor
  • Resistive Load - Unity Power Factor
 The Transformer is not a Load, it is a device which can transfer power not consume power. If you think that a Transformer is a Load that's wrong. So as the transformer does not consume power it can only transfer power with increasing and decreasing voltage and current that is why the Transformer ratings in KVA.
(2) When the transformer is designed the manufacturer does not know which type of load will be connected in future. And the power factor depends upon the load. If an Inductive Load is connected then the current will be lag which flows through the secondary winding of the transformer as well as the primary winding of the transformer.



Three Reasons Why Transformer Ratings in KVA, Why Transformer Ratings in KVA, not KW.



We also know that pure inductive and pure capacitive load does not practically exist. Every load has some resistance even it inductive or capacitive. For example, a motor is connected to the transformer which is inductive + resistive. So the motor draws both reactive(KVAR) and active power(KW). So the power supplied by the transformer is the vector sum of reactive(KVAR) power and active power(KW) that is KVA.
(3) The last reason is power loss. Most of the people think that is the main reason "Why Transformer Ratings in KVA" but I will say that is not the main reason. The first and second reason is more important which is described above.
The Copper loss(I2R)  occurs due to the flow of the current in the transformer winding and the Iron or core loss occurs due to the voltage. These losses do not depend on the power factor so that is why the transformer rating in KVA not KW.

 This is the Three Reasons Why Transformer Ratings in KVA.
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Saturday, November 10, 2018

November 10, 2018

Can DC Motor run on AC supply and Vice-Versa? Full Explanation.

Can DC Motor run on AC supply and Vice-Versa?



Can DC Motor run on AC supply and Vice-Versa? Full Explanation.



An electric motor is a machine which can convert electrical energy into mechanical energy. There are many applications of DC motor. Today we are going to know Can DC Motor run on AC supply and Vice-Versa? You may have this question in your mind so let's know.


Effect of AC supply on DC Motor.



(1) Effect of AC supply on DC Shunt Motor:


We already know that if we interchange the terminals of a DC shunt motor the rotation of the motor does not change. For the change the rotation of the DC Shunt Motor we must interchange the terminals of anyone either armature terminal or field terminal. So you can say that a DC Shunt motor can run on AC Supply.

 I also agree with you but it will not run perfectly because,
As the motor is DC so the field and armature winding made for DC supply. The winding which is made for DC always has more resistance than the winding which is made for AC. So when we give AC supply self-inductance will be produced in the winding which opposes the current which further decreases the production of flux. For this reason, the motor will be run in very less speed on AC supply.

When DC motor Runs on AC supply more loss and heat will occur in the motor.

 But one thing remembers that separately excited or permanent magnet DC Shunt motor will not run if the field is connected with DC Supply The motor will vibrate.


(2) Effect of AC supply on DC Series Motor:


We already know that in a DC Series motor the field winding has very less resistance than a DC Shunt Motor as the field is connected in series with the Armature Winding. So if we give AC supply on a DC Series Motor it will run perfectly. In fact, DC Series can run on both AC and DC supply. But the original AC series motor has the different construction from a DC series motor. Because of the manufacturer design the AC Series motor to reduce losses.




Effect of DC supply on AC Motor.




(1) AC motor cannot run on DC Supply because of most of AC motor like Single-Phase Induction Motors, Three Phase Induction Motors, Synchronous Motors need alternating flux, not static flux. As we know that only AC can produce alternating flux. So AC motor cannot run DC supply.

 (2) The other effect of the DC supply on the AC motor is that if we give DC supply on the AC motor then the windings of the AC motor may be burn because when the one reason is AC windings always have less resistance than DC windings and the other reason is when we give DC supply on the AC motor there are no Self-Inductance will be produced in the windings which can oppose the flow of current in case AC supply.

 So from the above explanation, we can say a DC motor may be run on AC supply but AC motor cannot run on DC supply.

 This is the full explanation of "Can DC Motor run on AC supply and Vice-Versa?" If you like this article please do share with your friends who are studying electrical engineering because it is a very important topic in electrical engineering. 


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Sunday, October 14, 2018

October 14, 2018

Capacitor Less Single phase Induction Motor: Shaded Pole Induction Motor Working and Application.

What is Shaded Pole Induction Motor? Working and Application of Shaded Pole Induction Motor.


Capacitor Less Single phase Induction Motor; Shaded Pole Induction Motor Working and Application.; shaded pole induction motor diagram; shaded pole motor advantages disadvantages; shaded pole motor efficiency; Capacitor Less Single phase Ind; Shaded Pole Induction Motor Wor; shaded pole induction motor dia; shaded pole motor advantages di;




There are different types of Induction Motors are available three phase as well as single phase. Single Phase Induction Motors are widely used in modern days. Shaded Pole Induction Motor is a single phase induction motor which can run without the capacitor that is why it is called Capacitor Less Single phase Induction Motor.

In this post, we are going to learn about Construction, Working, and Application of Shaded Pole Induction Motor. The construction and working of Shaded Pole Induction Motor are very simple.

Construction of Shaded Pole Induction Motor:

The Shaded Pole Induction Motor whose picture is shown in this article is collected from an old Refrigerator. We will discuss the applications of Shaded Pole Induction Motor.

Capacitor Less Single phase Induction Motor; Shaded Pole Induction Motor Working and Application.; shaded pole induction motor diagram; shaded pole motor advantages disadvantages; shaded pole motor efficiency; Capacitor Less Single phase Ind; Shaded Pole Induction Motor Wor; shaded pole induction motor dia; shaded pole motor advantages di;



      As you see in the above picture The Shaded Pole Induction Motor has a Main stator winding which is to be connected to the power supply during operation and Two Shaded winding or Shaded pole, a core, and a squirrel cage rotor.

The stator of the Shaded Pole Induction Motor has the salient poles. Each pole has their own exciting coil which are works by induction effect. 

STATOR of Shaded Pole Induction Motor:


Capacitor Less Single phase Induction Motor; Shaded Pole Induction Motor Working and Application.; shaded pole induction motor diagram; shaded pole motor advantages disadvantages; shaded pole motor efficiency; Capacitor Less Single phase Ind; Shaded Pole Induction Motor Wor; shaded pole induction motor dia; shaded pole motor advantages di;

Working of Shaded Pole Induction Motor:


                         Let's know how a Shaded Pole Induction Motor works. A rotating magnetic field is produced in the stator which causes the rotor to rotate. You may have a question of how rotating magnetic field is produced. Actually, the shaded coils or shaded poles create the rotating magnetic field. The effect of shading coils causes the main field flux to shift across the pole face from the unshaded portion to the shaded portion. 

                        The nature of this shifting flux lines is like a rotating field moving in the direction from the unshaded portion to the shaded portion. But one thing remembers that this rotating magnetic field not very strong like a three-phase induction motor. In the Shaded Pole Induction Motor, the working of rotating magnetic field only starts the rotor to rotate. 

                            When the rotor starts rotating an additional torque is developed by single-phase induction motor action. The motor ultimately attains a speed slightly less than synchronous speed and runs as single-phase induction motor.

Application of The Shaded Pole Induction Motor : 

As this type of motor is very simple of construction, they can be used in many places like small fans, Air conditioner, hair dryers, projectors etc. 


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October 14, 2018

Transformer can work on DC supply: Right or Wrong

Why Transformer Cannot work on DC Supply?


Transformer can work on DC supply: Right or Wrong, Step down transformer, 12V transformer

If you do not know how a transformer works. For going to the post click on " Working of a simple Transformer"
Now There is a question that is why a Transformer cannot work in DC? Let's know actually what happened when we apply DC supply on the Transformer.


To better understand this topic you should know about Faraday's Law.

      When DC supply is given to the primary winding of the transformer, current flow through the winding and as a result flux is also produced. As in the case of DC, the magnitude, and direction of the current does not change with time it remains constant. So the produced flux which linked both windings also does not change. According to the Faraday's law when the flux linking with the conductor changes the EMF will be induced on that conductor. As in this case, flux does not change so the EMF also is not produced.


     At the time when the switch gets ON the magnitude of the current increases from zero, the flux will be change and EMF will be produced. 
Again at the time when the switch gets OFF the magnitude of the current reduces to zero, the flux will be change and EMF will be produced.
But for both cases, time is very short. It is cleared that a Transformer cannot work on DC supply. 


Now there is a problem that if the DC supply is given to the transformer it's winding will be burn. Because the winding of the transformer has very low resistance. In the case of AC, as there EMF is produced which limits the current flowing through the coil. But in the case of DC, there is no EMF produced so a huge amount of current will be flow through the coil and the coil will be burnout.  
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October 14, 2018

Use Step Down Transformer in different ways.

Use Step Down Transformer in different ways.


In this post, you will learn the Use of Step Down Transformer in different ways.

(1) Have you known, how a Step-down transformer can be used as an Auto Transformer?

Yes, you can use a Step Down Transformer as an Auto Transformer very easily. The circuit diagram is given below. See the circuit diagram carefully and make the circuit properly. The connection of the terminal of the two winding is to be made as the circuit diagram.

As Step Up auto Transformer:



                                   how a Step-down transformer can be used as an Auto Transformer


As Step Down Auto Transformer:


how a Step-down transformer can be used as an Auto Transformer


(2) Let's know how a Step-Down Transformer can be used as Step Up Transformer?

You can use a Step-Down Transformer as a Step Up Transformer very easily using low voltage side as the primary side and high voltage side as the secondary side. But remember that only AC supply is to be given. The voltage can be applied up to the rated voltage.
use a Step Down Transformer as a Step Up Transformer

(3) How a Step Down Transformer can be used as a Current Transformer?

Use the low voltage coil of the Transformer as the primary coil and connect in series with the circuit whose current is to be measured. Connect an ammeter to the high voltage side. By calculating the ratio of the transformer you will measure current.

How a Step Down Transformer can be used as Current Transformer?



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