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calculator:inductance_of_straight_round_wire

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Calculator of inductance of a straight round wire

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Inductance of a straight wire or conductor with round (circular) cross-section can be calculated withe the equations as specified below.

Wire diameter d = 2·r =       Wire length l =      

      

L = Rosa, eq. (1)
L = Grover, eq. (2)
L = Paul, eq. (3a)
L = Paul, eq. (3b)
L = King & Prasad, eq. (4a)
L = Meinke & Gundlach, eq. (4b)
L = Aebischer & Aebischer, eq. (4c)

L = Average of all above

[1] Source: Edward B. Rosa, The self and mutual inductance of linear conductors, Department of Commerce and Labor, Bulletin of the Bureau of Standards, Volume 4, 1907-8, Washington, 1908
(1)
Rosa [1], eq. (9), p. ??
$$ L_{wire,round} = \frac{μ_0 ⋅ l}{2⋅π}⋅\left( ln \left( \frac{l+\sqrt{l^2 + r^2}}{r} \right) + \frac{1}{4} - \frac{\sqrt{l^2 + r^2}}{l} + \frac{r}{l} \right) $$ (H)
[2] Source: F.W. Grover, Inductance Calculations: Working Formulas and Tables, ISA, New York, 1982, ISBN 0876645570
(2)
Grover [2], eq. (7), p. ??
$$ L_{wire,round} = \frac{μ_0 ⋅ l}{2⋅π}⋅\left( ln \left( \frac{2⋅l}{r} \right) - \frac{3}{4} \right) $$ (H)
[3] Source: C.R. Paul. Inductance: Loop and Partial, Wiley-IEEE Press, 2009, New Jersey, ISBN 9780470461884
(3a)
Paul [3], full eq. (5.18b), p. ??
$$ L_{wire,round} = \frac{μ_0 ⋅ l}{2⋅π}⋅\left( asin \left( \frac{l}{r} \right) - \sqrt{1+ \left (\frac{r}{l} \right)^2} + \frac{r}{l} \right) $$ (H)
(3b)
Paul, [3] simplified eq. (5.18c), p. ??
for r « l
and for very high-frequency (infinitely thin skin depth)
$$ L_{wire,round} ≈ \frac{μ_0 ⋅ l}{2⋅π}⋅\left( ln \left( \frac{2⋅l}{r} \right) - 1 \right) $$ (H)
[4] Source: Aebischer H.A., Aebischer B., Improved formulae for the inductance of straight wires. Advanced electromagnetics. 2014 Sep 8;3(1):31-43
(4a)
King & Prasad [4] eq. (28), p. ??
$$ L_{wire,round} = \frac{μ_0 ⋅ l}{2⋅π}⋅\left( ln \left( \frac{2⋅l}{r} \right) - 1 + \frac{r}{l} \right) $$ (H)
(4b)
Meinke & Gundlach [4], eq. (29), p. ??
$$ L_{wire,round} = \frac{μ_0 ⋅ l}{2⋅π}⋅\left( ln \left( \frac{10⋅l}{4⋅r} \right) - 1 \right) $$ (H)
(4c)
Aebischer & Aebischer [4], eq. (34), p. ??
$$ L_{wire,round} = \frac{μ_0 ⋅ l}{2⋅π}⋅\left( ln \left( \frac{l+\sqrt{l^2 + r^2}}{r} \right) + \frac{1}{4} - \frac{\sqrt{l^2 + r^2}}{l} + \frac{0.905415⋅r}{l} \right) $$ (H)
where: $μ_0$ - permeability of vacuum (H/m), $l$ - wire length (m), $r$ - wire radius (m)
Note: Several assumptions are made for all these equations: 1) the length of the wire is significantly longer than it radius, 2) the medium and the wire are assumed to be non-magnetic with μr ≡ 1 (for magnetic wire see Calculator of inductance of a magnetic straight round wire), 3) the current is uniformly distributed (no skin effect, for high-frequency inductance see Calculator of inductance of a straight round wire at high frequency). The equations were converted here to be consistent with SI units.
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calculator/inductance_of_straight_round_wire.1736343250.txt.gz · Last modified: 2025/01/08 14:34 by stan_zurek

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