Coil Inductance: A Brief Introduction
We are continually faced with these objects, but unlikely to add any specific meaning to them. For us, this is commonplace. In fact, inductors are used in almost every device today but transformers are the most striking example of their use. If you think transformers are only usable at power substations, then you’re really mistaken: your laptop or mobile converter is a kind of transformer, only smaller than those used in power plants and distribution substations.
Any inductor consists of a winding and a core. The center is a rod of ferromagnetic or dielectric material on which the winding is wound. Most often this latter is made of copper wire.
The number of winding turns is directly related to the magnitude of the resulting coil’s magnetic induction. Now we’re going to think about what parameters and properties we ‘re going to determine before we start calculating the inductance of the coils and the formulas required for that.
What parameters does the inductance coil have?
The coil has many physical features reflecting its consistency and suitability for a specific job. One such is inductance. The ratio of the magnetic field flux produced by the coil to the magnitude of this current is numerically equal to. Inductance is expressed in Henry (GN), which takes values from microhenry units to hundreds of Henry in most cases.
Inductance is probably the coil’s most important parameter. And it’s not shocking that most people don’t even think there are other quantities that can characterize the coil ‘s actions and represent its suitability for a particular application.
Professionals also pay attention to loss-resistance when choosing an inductor. As you can understand from this expression, it represents the severity of the loss of electricity caused by spurious effects, such as heating wires, which occur in compliance with the Joule-Lenz law. It’s easy to understand that the better for the coil the lower the value. Another parameter that must be taken into account is the quality factor of the circuit. It is closely related to the previous parameter, which represents the active (loss resistance) reaction ratio.
Accordingly, the higher the quality factor, the better. The increase is achieved by choosing the optimal wire diameter, material and core diameter, and a number of windings.
Why do we need inductance calculation?
There are a great many different coil types in the world. They differ in properties, and hence in applications. Many are used in high strength transformers, others, solenoids, serve as high strength electromagnets. In addition to this, there are several inductor applications. And different types of coils are required for all of these. Their assets vary. But most of those properties can be combined using the inductance principle.
We have come close to describing what the formula requires for measuring a coil’s inductance. But it is worth noting that we are not talking about the “formula” but about the “formulas,” because all the coils can be separated into many broad classes, each of which has its own separate formula.
Types of Coils
The functionality differentiates between loop coils used in radiophysics, coupling coils used in transformers, and variometers, that is, coils whose output can be varied by adjusting the relative location of the coils. There’s even a coil kind, like chokes.
There is also a division within that class into ordinary and dual. They have a high resistance to alternating currents and very low resistance to direct currents, thanks to which they can act as a good filter that transmits direct current and alternating current delays. Dual chokes are more effective when compared to traditional ones at high currents and frequencies.
It is time we moved on to the article’s main subject. We begin by speaking about how to measure a coil ‘s core inductance. This is the simplest form of reckoning. Yet there are subtleties here too. Take a coil whose winding lies in a single layer, for simplicity.
For her, the single-layer inductor calculation is valid:
L = D 2 * n 2 / (45D + 100l )
Here L is the inductance, D is the coil’s diameter in centimeters, n is the number of twists, l is the winding length in centimeters. A single-layer coil assumes the thickness of the winding would not be more than one layer, meaning a flat inductor measurement is true for it. Most formulas for calculating inductances are usually very similar: major variations are in numerator and denominator only in the coefficients of the variables. The simplest here is the inductance measure of the coreless wire.
The formula for calculating the inductance of a coil with a great number of turns is also of interest:
L = 0.08 * D 2 * n 2 / (3 * D + 9 * b + 10 * c)
Here b is wire width, c is wire height. Such a formulation is efficient in measuring a multi-layer inducer. In practice, it is applied a little less frequently than the one that will be discussed below.
Perhaps most important would be measuring coil inductance with the core. There is a special formula that shows that the material from which the core is made, or rather, its magnetic permeability, determines that inductance. The design looks like this:
L = m * m 0 * n 2 * S / l
Where m is the core material ‘s magnetic permeability, m 0 is the magnetic constant (this is 12.56 · 10-7 Gn / m), S is the cross-sectional coil field, l-winding duration.
Calculating the inductor turns is very simple: that is the number of conductor wound layers on the center.
We’ve figured out the formulas, and now a little bit about exactly where these formulas and calculations can be handy.
Owing to the widespread distribution of inductors, these formulas are very commonly used. As we have already found out, various types of coils exist, each of which corresponds to its application. In this regard, separating them according to characteristics becomes necessary in some way, because each industry needs its own certain inductance and quality factor.
Basically, in manufacturing and in electrical engineering, measurement of the inductance of coils is used. Each hobbyist should be able to calculate the inductance, otherwise, they should be able to determine which coil of the vast array is suitable for their purpose and which not.
Are you interested?
Most scientists today are interested in magnetism and magnetic phenomena. Researchers studied both the magnetic and electrical sides of objects, seeking to find patterns and synthesize strong magnets with certain desired properties: with a high melting point or superconductivity for example. Many of these components can be found in a great many industries.
Let us give the aerospace industry an example: promising rockets with ion engines for long-range interstellar flights, which generate traction by ejecting ionized gas from the nozzle, are. The shock intensity in such an engine depends on the gas temperature and its velocity. Accordingly, to give the gas full acceleration power, we need a very powerful magnet that accelerates charged particles and also has a very high melting point so that when gases escape the nozzle, they don’t melt.
Never is intelligence superfluous, and always somewhere, so it comes in handy. Now, if you come across a coil inductance calculation system, you can easily say why exactly such formulas exist and what variables in them mean what. This article is intended only for your acquaintance, and if you want to learn more, you can read specialized literature (it has accumulated much after many years of researching magnetic phenomena).