Inductor Charging and Discharging

[hrerocker]

Inductor stores the energy in the form of Magnetic field. Current (AC) is the reason for inductor to store the energy. Suppose that a current in certain direction is charging an Inductor then will the direction of current remain same when the inductor will discharge or it will reverse?

 

[goldsmith]

Inductor stores the energy in the form of Magnetic field. Current (AC) is the reason for inductor to store the energy. Suppose that a current in certain direction is charging an Inductor then will the direction of current remain same when the inductor will discharge or it will reverse?

Hi hrerocker

You need to realize that what's the inductor in fact . inductor is nothing than a summer ! summer of magnetic fields ! how it can be yielded ? by twisting some turns of wire on a core or perhaps without core .
Every inductor follows from a well known formula ( law ) which has been called Lenz law . VL=L*(di/dt) for DC after five time constant there is no di/dt so the inductor will be saturated and it will behave as a wire only ! ( in steady state )
But for AC signals , you must know that inductor instead of every kind of signal ( DC/AC ) will deliver something which has been called inertia . it means it wants to make apposition instead of every situation that is new than it's former situation ! if you want give it a current it will deliver opposition . for example you have charged an inductor and then you want to cut the charging source , inductor will do something opposite than that to remain the former situation . that's all .

Is that clear now ?any question ?

Best Wishes
Goldsmith

 

[hrerocker]

GoldSmith, Your comments are appreciated.

The thing that i want to know is that Whether the direction of Charging and Discharging current will remain same or it will be Different.

Regards,
hrerocker

 

[FvM]

I doubt that "charging" and "discharging" are clear terms related to the the problem.

Can we agree that you are taling about increasing and decreasing the amount of stored energy?

For the simple case of constant inductance L, you get

E = 0.5 I² L

You see that stored energy is a function of the instantaneous current respectively it's square. So you need to increase/decrease the absolute current to increase or decrease the stored energy.

 

[muhammad11]

Power factor

Can anyone tell me what will happend when p.f becomes unity?
At unity p.f what will occur to resistive loads like bulb and inductive load like motors????

 

[smijesh]

GoldSmith, Your comments are appreciated.

The thing that i want to know is that Whether the direction of Charging and Discharging current will remain same or it will be Different.

Regards,
hrerocker

Direction of charging current and discharging current will be different.
Charged inductor having stored energy (1/2LI²), it will discharge when there is a path for reveres current flow. If there is no such path, the energy will drop gradually due to magnetic flux.

While charging, the current flow suppose right to left. After completing the charging if you disconnect, suddenly the polarity of the inductor will change (Left to right). So the discharge current flow in opposite direction.

 

[FvM]

Charged inductor having stored energy (1/2LI²), it will discharge when there is a path for reveres current flow.

The inductor voltage must be reversed, not the current. The inductor will "discharge" when the source driving the inductor current is switched of and the circuit allows the reverse voltage that is involved with a reduction of the inductor current.

If you e.g. short the inductor terminals, I will drop exponentially with the time constant L/Rcoil.

 

[BradtheRad]

The definition of an inductor is that it resists any change in current. It always 'tries' to make current go in the same direction and at the same intensity.

A coil generates counter-emf apruptly in response to any change in applied voltage. This EMF may increase or decrease suddenly, and it may change polarity suddenly.

Current will then respond gradually, governed by the inductive time constant (L / R). As this occurs, EMF weakens.

Click on links below to watch my Youtube videos about coil behavior. These consist of animated simulations.

They portray current flowing in wires, flux fields building and collapsing, changing EMF, etc.

Coil behavior with plain DC and pulsed DC.

https://www.youtube.com/watch?v=LVNxrN4jgvs

Coil behavior with AC (both square and sine waves).

https://www.youtube.com/watch?v=Os3jF9UeMoE