A reactor is an inductor

Inductance is the ratio of the magnetic flux of the conductor to the current that produces the alternating magnetic flux when the alternating current passes through the conductor.

When the DC current passes through the inductor, there are only fixed magnetic lines of force around it, which do not change with time; but when the AC current passes through the coil, there will be magnetic lines of force around it which change with time. According to Faraday's law of electromagnetic induction -- electricity generated by magnetism, the changing magnetic lines of force will produce induced potential at both ends of the coil, which is equivalent to a "new power supply". When a closed circuit is formed, the induced potential will produce an induced current. From Lenz's law, we know that the total amount of magnetic lines of force produced by induced current should try to prevent the change of magnetic lines of force. The change of the magnetic line of force comes from the change of the external alternating power supply, so from the objective effect, the inductance coil has the characteristic of preventing the current change in the AC circuit. Inductance coil has similar characteristics to inertia in mechanics. It is called "self induction" in electricity. Usually, when the knife switch is opened or turned on, sparks will occur. This self induction phenomenon is caused by high induction potential.

In short, when the inductive coil is connected to the AC power supply, the magnetic lines of force in the coil will change with the alternating current, resulting in the electromagnetic induction of the coil. The electromotive force produced by the change of the current of the coil itself is called "self induced electromotive force".

Function of inductor 1

Inductance and current in the coil are always the effect of self inductance in the coil. Inductance coil has a blocking effect on AC current. The blocking effect is called inductive reactance XL, and the unit is Ohm. The relationship between inductance L and AC frequency f is XL = 2 π fl. inductors can be divided into high-frequency and low-frequency choke coils.

Function of inductor 2

Tuning and frequency selection: LC tuning circuit can be composed of inductance coil and capacitor in parallel. That is to say, if the natural oscillation frequency f0 of the circuit is equal to the frequency f of the non AC signal, the inductive reactance and capacitive reactance of the circuit are also equal, so the electromagnetic energy oscillates back and forth in the inductance and capacitance, which is the resonance phenomenon of the LC circuit. When resonant, the inductive reactance and capacitive reactance of the circuit are equivalent and reverse, the inductive reactance of the total current of the circuit is the smallest, and the current is the largest (refers to the AC signal of F = "F0"). LC resonant circuit has the function of frequency selection, and can select the AC signal of a certain frequency f.

Function of inductor 3

The inductor has the functions of screening signal, filtering noise, stabilizing current and restraining electromagnetic interference.

Function of inductor 4

In electronic equipment, we often see the magnetic ring as shown in Figure 2. What are the functions of these small things? This kind of magnetic ring and the connecting cable form an inductor (the wire in the cable is wound with several coils of inductance on the magnetic ring). It is a common anti-interference element in electronic circuits. High frequency noise has a good shielding effect, so it is called absorption magnetic ring. It is usually made of ferrite material, also known as absorption magnetic ring Ferrite magnetic ring. In Figure 2, the above is an integrated magnetic ring, which is a magnetic ring with mounting clip. Magnetic rings have different impedance characteristics at different frequencies. At low frequency, the impedance is very small. When the signal frequency increases, the impedance of the magnetic ring increases sharply.

As we all know, the higher the frequency of the signal, the more it radiates out. However, all the signal lines have no shielding layer. These signal lines become good antennas to receive all kinds of messy high-frequency signals in the surrounding environment. When these signals are superimposed on the transmitted signals, they will even change the transmitted useful signals, seriously interfere with the normal work of electronic equipment, and reduce the electromagnetic interference of electronic equipment Disturbance (EM) has been considered. Under the action of the magnetic ring, even if the normal and useful signals pass smoothly, the high-frequency interference signals can be well suppressed, and the cost is low.