Page 279 - Electrical Engineering Dictionary

female connector a connector present- an external magnetic field is applied. It is
ing receptacles for the insertion of the corre- used in ferrite loaded loop antennas, for ex-
sponding male connector that presents pins. ample, to increase the flux through the loop
antenna.
fenestration any opening or arrangement
of opening (normally filled with media for ferroelectric material a polar dielectric
control) for the admission of daylight. in which the crystallographic orientation of
the internal dipole moment can be changed
Ferranti, Sebastian Ziani de (1864– by the application of an electric field.
1930) Born: Liverpool, Lancashire, England
Ferranti is best known for developing sys- ferrofluid iron based solution employed
tems of high-voltage AC power systems. The in voice coil/pole piece gap improving mag-
generating and transmission systems he de- netic flux and power handling capacity.
signed still form the basis for most modern
power systems. As a principal in the London ferromagnetic materials in which inter-
Electric Supply Corporation, Ltd., Ferranti nal magnetic moments spontaneously line up
demonstrated that high-voltage AC current parallel to each other to form domains, re-
could be distributed and then stepped down sulting in permeabilities considerably higher
for use in a more efficient and economical than unity (in practice, 1.1 or more); exam-
system than the smaller DC current systems ples include iron, nickel, and cobalt.
then operating. Ferranti invented a number
of other devices and systems as a consultant ferroresonance a resonant phenomenon
and in his own company. He was named pres- involving inductance that varies with satura-
ident of the Institute of Electrical Engineers tion. It can occur in a system through the
in 1911. interaction of the system capacitance with
the inductance of, for example, that of an
ferrite a term applied to a large group open-circuited transformer. Ferroresonance
of ceramic ferromagnetic materials usually resembles, to some extent, the normal reso-
consisting of oxides of magnesium, iron, and nance that occurs wherever L-C circuits are
manganese. Ferrites are characterized by encountered. If the capacitance is apprecia-
permeability values in the thousands and are ble, ferroresonance can be sustaining or re-
used for RF transformers and high Q coils. sult in a limited over voltage enough to dam-
age the cable or the transformer itself.
ferrite beads small toroids made of fer-
rites which are slipped over a conductor in ferroresonant transformer a trans-
order to suppress RF currents. The beads act former that is designed to operate as a tuned
as RF chokes at high frequencies. circuit by resonating at a particular fre-
quency.
ferrite core a magnetic core made up
of ferrite (compressed powdered ferrromag- Fessenden, Reginald Aubrey (1866–
netic) material, having high resistivity and 1932) Born: East Bolton, Quebec, Canada
low eddy current loss. Fessenden is best known as a radio pio-
neer who described the principle of ampli-
ferrite core memory See magnetic core tude modulation and the heterodyne effect.
memory. Fessenden became the chief scientist at Edi-
son’s laboratory and then spent two years
ferrite material a material that has very with Westinghouse. He later held teaching
low conductivity (σ) and very large perme- posts at Purdue University and Western Uni-
ability (µ). Its properties can be altered when versity of Pennsylvania (now the U. of Pitts-

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