Page 251 - Electrical Engineering Dictionary

Electromagnetic spectrum.

mechanical coherence. Depending on the angle δ as a function of time. Examination of
quantum mechanical system, electromagnet- all the Swing curves (plot of δ w.r. to time)
ically induced transparency can be viewed as shows whether the machines will remain in
a special case of effects such as Fano interfer- synchronism after a disturbance. See also
ence or coherent population trapping applied swing equation.
to optically dense media.
electromechanical relay a protective re-
electromagnetics the study of the effect
lay that uses electrical, magnetic, and me-
of electric charges at rest and in motion.
chanical circuits to implement the operating
logic.
electromechanical equation a basic non-
linear equation that governs the rotational dy-
electron band a range or band of energies
namics of a synchronous machine in stability
in which there is a continuum (rather than a
studies. The equation is given by
discrete set as in, for example, the hydrogen
2
2Hd δ/ω s dt 2 atom) of allowed quantum mechanical states
partially or fully occupied by electrons. It
where H is a constant defined as the ra- is the continuous nature of these states that
tio of the kinetic energy in megajoules at permits them to respond almost classically
synchronous speed to the machine rating in to an applied electric field.
MVA, ω s is the synchronous speed in rads
per second, and δ is the load angle expressed electron beam excitation electron impact
in electrical degrees. Various forms of the excitation due to a free electron beam rather
swing equation serve to determine stability than, for example, the conduction electrons
of a machine within a power system. So- in a gas discharge; permits high-pressure ex-
lution of the swing equation yields the load citation without arcing.

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