Understanding Inductors: How They Oppose Changes in Current
” During my school days, one question often came to my mind: why does a coil of wire behave differently from the same wire when it is stretched out straight?
After some search i find out
Straight conductor → potential difference →current → Power flow
Round coil → potential difference → current →magnetic field → changing current → induced EMF → inductance
In this post, We are going to discuss “INDUCTORS”.
INDUCTOR
” Inductor is a from of coil in which number of turns of insulated wires been wrapped. It stores energy in the form of electromagnetic field. Ferromagnetic material may or may not be sandwiched as a core inside the coil. Inductor is a two terminals passive element which is available in different shapes & sizes.”
Air core inductor
Any conductor which is having; Current flowing through it, Magnetic field get generated around that conductor. Since in inductor, Wires are been wrapped into the circular motion that’s why magnetic field from all the turns; links to each other. Due to extra magnetic field linking in circular coil if comparison with Straight conductor’s magnetic field; Extra emf get generated in the inductor.
The generated emf in such a direction that it always oppose the power supply which has generated it. It oppose the change in current when current increasing in the circuit & It helps to maintain the current when current decreasing in the circuit. Inductor obey the Lenz’s law.
Toroidal shape Inductor
Now, The answer of that above question is :
In conductor, To oppose the electric current there is only resistance While in inductor along with resistance there is BackEMF. That generated emf is always in a direction to oppose the change which has generated it.
INDUCTANCE
The inductor is characterized with the term inductance (L). It is the tendency of conductor to oppose the change of electrical current flowing through it.
For a general inductor:
L = λ / I
where λ is flux linkage.
If there are N turns and each turn links the same flux Φ:
λ = NΦ
so:
L = NΦ / I
The units of inductance is Henry.
Since the inductance of the inductor depends upon flux linkage which means it ultimately depends upon the geometrical shape of current flow & surrounding material of inductor. That’s why inductors are designed in circular form & core is being sandwiched with ferromagnetic material in between the coil to increase the inductance up to multiple times.
APPLICATIONS OF INDUCTOR
Electromagnets
Electromagnetism play a very important role in Electrical System. An Electromagnet is a type of inductor Which behave like a magnet when power supply get connected across it. AC as well DC operated, Electromagnets are available.
In Contactors, Relays, Circuit Breakers, Electric bells & many more electrical products are there in which electromagnet is the key component. In these type of products; In along with electromagnet, Spring mechanism is being used in Such a way that when coil get magnetized it pulled down & when coil get demagnetized, System get pushed away automatically.
Parts inside the Contactor in Which electromagnet the main component
Transformers are the powerful Electrical machines which are used widely all around the world. Transformers transform power from one circuit to another statically without any type of movement with higher efficiency.
A Transformer works on the principle of mutual induction between two magnetically coupled windings.”Generally, It has two windings primary & secondary. Primary gets power supply as an input while power at secondary side get transferred magnetically.
Power & frequency at both the sides; Input-output remains the same in Transformers . It is the voltage & current which changes accordingly. By changing the number of turns in Primary & secondary windings, voltage level can be adjusted.
Low rating small Transformers
Transformer 500KVA having a voltage ratio 11000/400
Line Reactors
Non linear loads like variable frequency drives, Rectifiers & SMPS produces harmonics in the circuit Which increases the losses in the system. For the preventions of harmonics & transients in the circuit, Line Reactors are being connected in the circuit just before the non linear loads.
“Harmonics are the unwanted signals with higher frequency sizes which are the multiple times of fundamental frequency.”
The property of inductor to oppose the change in line current which is flowing through it; is used in Line reactors. Line reactor impede harmonic currents/ reduce harmonic effect.
3 Phase line Reactors/Choke connected Infront of 2.2kW VFD
Electrical Motors
Electrical motors are the powerful Electrical machines which transforms electrical power into mechanical power. Electrical motors are working on the principle of faraday law of electromagnetic induction.
5.5 KW-960rpm 3phase415Volts Induction motor
Filter Circuits
Inductive reactance=2*π*f*L
Capacitive reactance= 1/(2*π*f*C)
Where; f is frequency, L is inductance, C is capacitance
Inductive reactance is directly proportional to frequency which means higher the frequency, higher will be the Inductive reactance.
Capacitive reactance is inversely proportional to frequency which means higher the frequency leads to lower capacitive reactance.
As per above calculation, Inductors in comparison to capacitors opposes more to the flow of alternating current. While it is reverse in direct current, Inductor opposes less to the flow of electrical current. With Appropriate calculation according to the requirement, Inductors or capacitor or combination of both can be connected in way to obtain the filter circuit. These filter circuits are used to pass particular type of power supply.
SUM UP
Inductor is a from of coil in which number of turns of insulated wires been wrapped. It stores energy in the form of electromagnetic field.
Inductor is a two terminals passive element which is available in different shapes & sizes.
Ferromagnetic material may or may not be sandwiched as a core inside the coil.
Inductor follows ‘Lenz’s law’ According to which; Generated emf in inductor is always in a direction to oppose the change in current which has generated it.
The Inductor is characterized with the term inductance (L).
Inductance is the tendency of conductor to oppose the change of electrical current flowing through it.
The units of inductance is Henry.
Applications of Inductor are- Electromagnets, Transformers, line reactors, Electrical Motors, Generators & Filter circuits.
Hope, You like the post. If you have any doubt, Suggestion or query Please do comments !
One Response