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The reciprocal of reluctance in a magnetic circuit. It is the analog of conductance (the reciprocal of resistance) in an electric circuit, and is given by

Eq. (1), where B is the magnetic flux density, H is the magnetic field strength, and the integrals are respectively over a cross section of the circuit and around a path within it.

From Eq. (1), it can be shown that Eq. (2) is valid, where A

is the cross-sectional area of the magnetic circuit, l its length, and μ the permeability. If the material is ferromagnetic, as is often the case, then μ is not constant but varies with the flux density and the complete magnetization curve of B against H may have to be used to determine the permeance. See Reluctance


A characteristic of a portion of a magnetic circuit, equal to magnetic flux divided by magnetomotive force; the reciprocal of reluctance. Symbolized P.


A measure of a material’s resistance to water-vapor transmission, expressed in perms. Equal to the ratio of (a) the rate of water vapor transmission through a material or assembly between its two parallel surfaces to (b) the vapor pressure differential between the surfaces.
References in periodicals archive ?
The units of permeability and permeance across the membrane are given in Table-1 [7].
Fibers were potted in modules as described in the experimental section and connected to the permeation system to measure nitrogen permeance at constant pressure.
Permeance is lower near the corners of a magnet, making these areas more susceptible to demagnetization.
is the permeance of airgap with restriction of a slotted stator and a smooth rotor and
The functionalized MIL-53 incorporated MMHFM obtained 30.9 GPU of C[O.sub.2] permeance and also exhibited excellent C[O.sub.2]/[N.sub.2] selectivity of 34.7, as presented in Table 2.
The water vapor permeance of a single layer of coated paper over a range of RH conditions is listed in Table 2.
In addition, the calcination process creates a porous structure, i.e., increases air permeance (Fig.
From Figure 2, it can be clearly seen that the amplitudes of most harmonics are reduced in the air gap since the different permeances exist in the full flux path from stator yoke to air gap.
where reluctance R is the inverse of permeance, the flux path length for each element is L, and flux path width W is simplified to the width of the core.
Oxygen permeance tests were performed by mounting the respective containers to Mocon OXTRAN devices, continually flushing the containers with nitrogen, and subsequently determining oxygen ingress through the container sidewall.