permeance (redirected from permeances)

permeance [′pər·mē·əns]

(electromagnetism)

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

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Permeance

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

(1) 

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

(2) 

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