# Calculation formula and unit of inductance | GETWELL

## Inductance calculation formula

### Coil formula:

Impedance (Ω) = 2 * 3.14159 * F (frequency) * inductance (H), set with 360 Ω impedance, so:

Inductance (H) = impedance (Ω) present (2 * 3.14159) present F (frequency) = 360 present (2 * 3.14159) present 7.06 = 8.116 H

### According to this, the number of winding can be calculated:

Winding number =[inductance * {(18* coil diameter (inch)) + (40 * coil length (inch))}] ÷ coil diameter (inch)

Laps = [8.116 * {(18 * 2.047) + (40 * 3.74)}] present 2.047 = 19 times

### Calculation formula of hollow inductance

Calculation formula of hollow inductance: L (mH) = (0.08D.D.N.N)/(3D+9W+10H)

D -- coil diameter

N -- the number of turns in the coil

D - wire diameter

H -- coil height

W -- coil width

The units are mm and mH.

### Calculation formula of inductance of hollow coil:

L = (0.01*D*N*N)/(l /D+0.44)

Coil inductance: l, unit: micro - heng

Coil diameter: D, unit: cm

Coil turns: N, unit: turns

Coil length: L, unit: cm

### Calculation formula of frequency inductance capacitance:

L = 25330.3 / [c] (f0 * f0) *

Operating frequency: f0 unit :MHZ f0=125KHZ=0.125

Resonant capacitance: c unit :PF c=500...1000pf May be determined by itself, or by Q

Values determine

Resonant inductance: l unit: micro - harmonic

### The calculation formula of coil inductance

1. For circular CORE, the following formula can be used :(IRON)

L=N2. AL L= inductance (H)

H-dc =0.4 NI/l N= number of turns

AL is equal to the inductance

H-dc = DC magnetization force I= through current (A)

L = magnetic circuit length (cm)

The values of l and AL can be referred to the Micrometal comparison table.For example, if the coil is made of t50-52 material and has 5 1/2 coils, its L value is t50-52 (indicating OD is 0.5 "), and its AL value is about 33nH according to the table

L = 33 (5.5) = 998.25 2 nH ≒ 1 mu H

When the current is flowing through 10A, the change of L value can be shown as L =3.74 (refer to the table).

H-dc =0.4 NI/l =0.4 ×3.14×5.5× 10/3.74 = 18.47 (after looking up the table)

You can see how much the L value decreased (3% I %)

2. Introduce an empirical formula

### Among them

The permeability of the vacuum is 4 times 10 (-7).10 to the minus 7.

Where, s is the relative permeability of the magnetic core inside the coil; where, is s=1

N2 is the square of the number of loops

The cross-sectional area of the S coil, in square meters

L the length of the coil, in meters

The k coefficient depends on the ratio of the radius (R) to the length (l) of the coil.

The calculated inductance is in Henry (H).

## Unit of inductance

Inductance symbol: L

Unit of inductance: heng (H), milliheng (mH), micro heng

H=10^3mH=10^6 H=10^9nH.

Conversion: 10X10 to the NTH power if 103 is 10X10 to the third nh is 10uh

In addition to the general inductance and precision inductance

General inductance: the error value is 20%, expressed by M;The error is 10%, in terms of K.

Precision inductance: error value is 5%, represented by J;The error is 1%, in terms of F.

For example, 100M is 10 H, with an error of 20%.