Page 250 - Electrical Engineering Dictionary

electromagnetic environmental effects electromagnetic radiation an electro-
encompasses all electromagnetic disciplines, magnetic wave created by the acceleration or
including electromagnetic compatibility deceleration of charge.
(EMC); electromagnetic interference (EMI);
electromagnetic vulnerability (EMV); elec- electromagnetic smart materials ma-
tromagnetic pulse (EMP); radiation hazard terials such as shielding materials, radar-
(RADHAZ) (hazard of electromagnetic ra- absorbing materials (RAMs), and electro-
diation to personnel, ordnance, and fuels magnetic surface materials, in all of which
(HERP, HERO, HERF)); lightning, p-static; some electromagnetic properties can be
electrostatic discharge (ESD), and emission adaptively controlled by means of an external
control (EMCON). stimulus dictated by the sensed electromag-
netic response.
electromagnetic interference (EMI) (1)
any electromagnetic disturbance that inter- electromagnetic spectrum the frequency
rupts, obstructs, or otherwise degrades or and wavelength of electromagnetic radiation.
limits the effective performance of electron- We have the following classification reported
ics/electrical equipment. It can be induced in the figure, while the microwave frequency
intentionally, as in some forms of electronic band designations is reported in the table.
warfare, or unintentionally, as a result of a
spurious emissions and responses, intermod-
ulation products, and the like. Additionally, electromagnetic susceptibility a device’s
EMI may be caused by atmospheric phenom- failure to perform appropriately if there is an
ena, such as lightning and precipitation static electromagnetic disturbance.
andnon-telecommunicationequipment, such
as vehicles and industry machinery. electromagnetic torque the torque pro-
(2) unwanted high-frequency electrical duced in a machine by the interaction of the
signals, also known as radio frequency in- magnetic fields and/or by the varying reluc-
terference (RFI), which can be generated by tance principle where the field attempts to
power electronic circuits switching at high maximize its intensity in a machine during
frequencies. The signals can be transmit- electromechanical energy conversion.
ted by conduction along cables (450 kHz to
30 MHz) or by radiation (30 MHz to 40 GHz) electromagnetic vulnerability (EMV)
and can interfere with control or other elec- the inability of a device, equipment, or sys-
tronic equipment. tem to perform without degradation when
subjected to electromagnetic environment of
electromagnetic interference filter a fil- a specified power level and frequency range.
ter used to reduce or eliminate the electro-
magnetic interference (EMI) generated by electromagnetic wave wave in which the
the harmonic current injected back onto the electric and magnetic variables are solutions
input power bus by switching circuits. The of the Maxwell–Heaviside equations.
harmonic current is caused by the switch
action that generates switch frequency rip- electromagnetic wave propagation the
ple, voltage and current spikes, and high- phenomenonofelectromagneticenergyprop-
frequency ringing. Generally called an EMI agating in the form of waves of the coupled
filter. electric and magnetic field intensity vectors.

electromagnetic pulse (EMP) a large electromagnetically induced transparency
impulsive-type electromagnetic wave gener- a technique to render optically dense media
ated by nuclear or chemical explosions. transparent by using a long-lived quantum

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2000 by CRC Press LLC