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14.8.
Sources of interferences
Sources result from the redistribution of electromagnetic energy. Such
redistributions and their most important sources are listed below.
- Stationary and non-stationary transmitters
Both stationary high power radio transmitters and non-stationary walkie-
talkies operating in the immediate vicinity of systems or equipment, lead to
uncontrolled electromagnetic irradiation into vulnerable electronic
equipment.
Parameters
:
narrow-band, continuous electromagnetic interferences
(modulated).
E-fields and/or H-fields
power
mains
Radiation
Conducted
----
- Electrical fast transients (burst)
Electromagnetic influences produced in the neighborhood of a device by
rapid variation of voltage and current . This is the result of the abrupt
change of a switch from a non-conductive to a fully conductive status or
vice versa, e.g. switching inductive loads with mechanically moved
contacts between which arcing occurs before they separate. Further
examples are provided by flash-overs in the measuring and limiting spark
gaps used in high voltage test facilities.
Parameters:
broad-band pulse interferences, rise time of the pulses of a
few nanoseconds, small energy content and high repetition
rate.
