Best Electrical & Electronics Websites for Learn

Which are the best Electrical & Electronic Websites for Learn?

Following are the websites for Electrical & Electronics Learning 

1. NPTEL E-Learning Courses
2. Electrical Engineering Portal 
3. Electrical4u
4. All About Circuits 
5. 
   

Some basic concepts of Magnetism & Electromagnetism

MAGNETISM AND ELECTROMAGNETISM

Magnetic Materials

A substance that has the property of being attracted by or attracting the magnet is known as Magnetic Material. 

Three Classes of this are 

1. Paramagnetic Materials

2. Diamagnetic Materials

3. Ferromagnetic Materials

Paramagnetic Materials Example

Ferromagnetic Materials Example 

Magnetic Field :

Space around the poles of a magnet is called the magnetic field, & is represented by magnetic lines of force.

Magnetic Field 

Magnetic Force :

The force Exerted on one magnet by another, either attraction or repulsion, is known as Magnetic force. 

Examples - Compass, Motor, Train Tracks & Roll Coasters

Magnetic Force 

Coulomb's Law :

First Law

Unlike Poles attract each other & like poles repel each other.

Second Law

The force between two magnetic poles 

i)      Directly proportional to the product of their pole strengths.

ii)     Inversely proportional to the square of the distance between them.

iii)    Depends on the medium in which the poles are placed.

Where,

Magnetic Strengths of Magnetic Poles = m1 & m2

Distance between two magnetic poles = r

Permeability of the medium = u

The force of attraction or repulsion between two magnetic poles = F.

Relative Permeability (ur)

The ratio of the force between two magnetic poles placed at a certain distance in the air to the force between them placed at the same distance in that medium.

Relative Permeability

Magnetic Field Strength (H) 

Force experienced by a unit north pole placed at that point.

Represented By H.

It is a Vector Quantity. 

Magnetic Field Strength

Magnetic Potential

Work required to move the unit (one weber) north pole from infinity to that point against the magnetic force.

It is a Scaler Quantity,

i.e. it has magnitude only.

Magnetic Lines of Force 

What is power factor Correction?

Power Factor Correction

What is power factor correction?

• A technique used to improve the power factor of ac circuits by reducing the reactive power present in the circuit. 
• The main target for power factor correction is to increase the efficiency of the circuit & reduced the current drawn by the load.
• It reduces the phase shift between voltage & current, so it tries to keep the power factor to unity.
• The most economical value is between 0.9 to 0.95.

Need for power factor correction

• In AC Circuits, voltage & current are sinusoidal waves. Hence, the magnitude & direction changes continuously. At the particular instant of time, the power dissipated is a multiplication of voltage & current at that instant.
• If an AC circuit having inductive loads having a winding, chowk coils, solenoid, transformer the current is out of phase with the voltage.

Power Factor Correction Circuit

• For power factor correction we mainly used Capacitor, Capacitor Bank, and Synchronous condenser.
• According to equipment used there are 3 types

1. Capacitor Bank
2. Synchronous Condenser
3. Phase advancer

Capacitor Bank

Synchronous Condenser

Phase Advancer

Applications of Power factor Correction

1. In the transmission network high power factor is necessary. by using Power factor correction methods high power losses reduced & voltage regulation improved.

2. In an industrial plant induction motor used. This method reduced heat dissipation and Improved the efficiency of the system.

3. PFC Equipment reduces heat generation of the cables, alternator, switchgear, etc.

4. Generate less energy due to the high efficiency of the network. this reduces carbon emission. 

What is a difference between Transformer & Induction Motor?

What is the difference between Transformer & Induction Motor?

1.  Induction Motor is fundamentally a transformer in which the stator is the primary & the rotor is short-circuited secondary.
2. The rotor is a stationary part of the induction motor. The rotor current establishes a flux that opposes & tends to weaken the stator flux. because of this more current flows through the stator winding. This can be the same happen the secondary current in a transformer causes a corresponding increase in the primary current of the transformer.
3. The working principle of both transformer & Induction motor is the same.

 Main Difference in Transformer & Induction Motor

1. A transformer is a static device whereas, Induction Motor is a dynastic machine.
2. Transformer efficiency is always higher compared to induction motor because there are no moving parts present in this static machine. whereas, in induction motor have mechanical losses occurs.
3. An iron core is used as a medium for the passage of flux in the transformer & in an induction motor, the air gap is used between rotor & stator.
4. The frequency of induced EMF & current in the secondary is the same in the transformer whereas the frequency of the rotor is variable.
5. A transformer is an alternating flux machine while an induction motor is a rotating flux machine.
6. Transformer transfers electrical power whereas induction motor converts electrical power into mechanical power.
7. Operate at any kind of power factor depends on the load while induction motor operated on lagging power factor.
8. In a transformer, both the input & output energy is in the form of electrical energy whereas, in an electrical induction motor input is electrical energy & output is in the form of mechanical energy.