What Is the Inductance of a Solenoid?

The single-layer coil is wound around the paper tube or bakelite skeleton with insulated wires one by one. Such as transistor radio medium wave antenna coil.

For single-layer cylindrical coil inductance: its inductance value has an approximately exponential relationship with the number of coils and the diameter of the coil and a logarithmic relationship with the length of the coil. At the same time, it can be seen that the specific relationship is different for different l / D ratios.

Influence of heart on inductance under different coil connection modes:

1. The inductance value in the total circuit using different connection methods is different.

Inductance (inductance coil) is used

1. If the hive coil is wound,

The main parameters of inductance include inductance, allowable deviation, quality factor, distributed capacitance and rated current.

(1) Inductance The inductance is also called the self-inductance coefficient, which is a physical quantity that indicates the self-induction ability of the inductor.

The amount of inductance mainly depends on the number of turns (turns) of the coil, the winding method, the presence or absence of the core and the material of the core, and so on. Generally, the larger the number of coil turns and the denser the coils, the greater the inductance. A coil with a magnetic core has a larger inductance than a coil without a core; a coil with a larger magnetic permeability has a larger inductance.

The basic unit of inductance is Henry (referred to as Henry), which is represented by the letter "H". Commonly used units are millihenry (mH) and microhenry (H). The relationship between them is: 1H = 1000mH; 1mH = 1000H

(II) Allowable deviation Allowable deviation refers to the allowable error value between the nominal inductance on the inductor and the actual inductance.

Generally, the inductance used in circuits such as oscillation or filtering requires high accuracy, and the allowable deviation is ± 0.2% ~ ± 0.5%; while the accuracy for coils used for coupling and high-frequency choke is not high; the allowable deviation is ± 10% ~ 15%.

(3) Quality factor Quality factor is also called Q value or figure of merit, which is the main parameter to measure the quality of inductor. It refers to the ratio of the inductive reactance and the equivalent loss resistance of the inductor when it is operated under an AC voltage of a certain frequency. The higher the Q of an inductor, the lower its loss and the higher its efficiency.

Quality factor Q:
A physical quantity representing the quality of the coil, Q is the ratio of the inductive reactance XL to its equivalent resistance, ie: Q = XL / R. The higher the Q of the coil, the smaller the loop loss. The Q of the coil and the DC resistance of the wire , The dielectric loss of the skeleton, the loss caused by the shield or the iron core, the influence of high-frequency skin effects and other factors. The Q value of the coil is usually tens to one hundred.

The quality factor of the inductor is related to the DC resistance of the coil wire, the dielectric loss of the coil bobbin, and the loss caused by the core, shield, etc.

(IV) Distributed capacitance Distributed capacitance refers to the capacitance existing between the turns of a coil and between the coil and the core. The smaller the distributed capacitance of an inductor, the better its stability.

(5) Rated current The rated current refers to the maximum current value allowed to pass when the inductor is in normal operation. If the working current exceeds the rated current, the inductor will change its performance parameters due to heat generation, and even burn out due to overcurrent.