GLOSSARY OF TERMS
GLOSSARY OF TERMS
Air Core Inductance – Lo (henry)
The inductance that would be measured if the core had unity permeability and the flux distribution remained unaltered.
Coercive Force – Hc (oersted or A/m)
The magnetized field strength required to bring the magnetic flux density of the magnetized material to zero.
Core Constant – C1 (cm-1)
The summation of the magnetic path lengths of each section of a magnetic circuit divided by the corresponding magnetic area of the same section.
Core Constant – C2 (cm-3)
The summation of the magnetic path lengths of each section of a magnetic circuit divided by the corresponding magnetic area of the same section.
Curie Temperature – Tc (oC)
The transition temperature above which a ferrite loses its ferromagnetic properties.
Disaccommodation – D
The proportional decrease of permeability after a disturbance of magnetic material, measured at constant temperature, over a given time interval.
Disaccommodation Factor – DF
The disaccommodation factor is the disaccommodation after magnetic conditioning divided by the permeability of the first measurement times log10 of the ratio of time intervals.
Effective Dimensions of a Magnetic Circuit –
Area Ae (cm2), Path Length le (cm), and volume Ve (cm3)
For a magnetic core of given geometry, the magnetic path length, the cross sectional area, and the volume that a hypothetical toroidal core of the same material properties should possess to be the magnetic equivalent to the given core.
Field Strength – H (oersted or A/m)
The parameter characterizing the amplitude of the alternating field strength.
Flux Density – B (gauss or mT)
The corresponding parameter for the induced magnetic field in an area perpendicular to the flux path.
Flux Density, saturation – Bs (gauss or mT)
The maximum intrinsic induction possible in a material.
Inductance Factor – AL (nH)
Inductance of a coil on a specified core divided by the square of the number of turns. Unless otherwise specified, the inductance test conditions for the inductance factor are at flux density < 10 gauss.
Loss Factor – tan δ / μi
The phase of displacement between the fundamental components of the flux density and the field strength divided by the initial permeability.
Magnetic Constant – μo
The permeability of free space. µ0 = 4π × 10−7 H·cm
Magnetic Hysteresis –
In the magnetic material, the magnetization charge present in the material causing an offset in the B-H loop as a result of this ‘memory’ effect.
Magnetically Soft Material –
A magnetic material with low coercivity. A material which holds little or no residual magnetic charge.
Permeability, amplitude – uΔ
The quotient of the peak value of the flux density and the peak value of the applied field strength at a stated amplitude of either, with no static present.
Permeability, complex series – μs’, μs”
The real and imaginary components respectively of the complex permeability expressed in series terms.
Permeability, effective – μe
For a magnetic circuit constructed with an air gap or air gaps, the permeability of a hypothetical homogeneous material which would provide the same reluctance.
Permeability, incremental – μΔ
Under stated conditions the permeability obtained from the ratio of the flux density and the applied field strength of an alternating field and a superimposed static field.
Permeability, initial – μi
The permeability obtained from the ratio of the flux density, kept at < 10 gauss, and the required applied field strength. Material initially in a specified neutralized state.
Power Loss Density – P (mW/cm3)
The power absorbed by a body of ferromagnetic material and dissipated as heat, when the body is subject to an alternating field which results in a measurable temperature rise. The total loss is divided by the volume of the body.
Remanence – Br (gauss or mT)
The flux density remaining in a magnetic material when the applied magnetic field strength is reduced to zero.
Temperature Coefficient – TC
The relative change of the quantity considered, divided by the difference in the temperatures producing it.
Temperature Factor – TF
The fractional change in the initial permeability over temperature range, divided by the initial permeability.