Ecotech GTS Control Logic RIV-601P/S, Техническое описание и руководство по применению

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MASP 27-GB
rev. 0 NOV10
3.0 Sources of electromagnetic emissions
There are lots of electrical equipment which can generate
electromagnetic noise. Here is a short list of the main ones.
3.1 Radio and television transmitters
Their electromagnetic field is modulated by sound and im-
age.
3.2 Radio-telephone transceivers
Their electromagnetic field is modulated by voice.
3.3 Mobile phone transceivers
Their electromagnetic field is intermitted and modulated
both by connection impulses which keep mobile phone
under control and by voice.
3.4 Frequency converters for variable speed electric
motors
This electronic equipment control frequency and power by
electrical pulse trains with variable time length and repeti-
tion frequency. The electrical pulses steep fronts generate
electromagnetic noise.
3.5 Uninterruptible power supplies
Uninterruptible power supplies are built with electronic
50-60Hz frequency generators and are supplied by DC power
supplies. Frequency is generated by electrical pulse trains
with variable time length and repetition frequency.
The electrical pulses steep fronts generate electromagnetic
noise.
3.6 Switching power supplies
Switching power supplies are DC power supplies which
control the level of voltage and current by electrical pulse
trains with variable time length and repetition frequency.
The electrical pulses steep fronts generate electromag-
netic noise.
3.7 Industrial computers for production processes
Their connection to equipment and other electrical devices
is done by electrical pulse trains of high intensity running
through long cables.
3.8 High frequency generators for plastic welding
machines
They behave like powerful radio transmitters built into in-
dustrial equipment, and are activated periodically for short
periods during welding. The same high frequency generators
are used in the woodworking industry to heat and bend the
parts to be curved and shaped.
3.9 On-off switches for electrical motors
At the starting and stopping of the motors the switch contacts
generate strong electrical arcs caused by inrush currents and
its contact behavior on opening and closing. The opening
arc is particularly strong because of high induction values in
the motor. The related electromagnetic pulsing field covers
all the surrounding environment and runs through all the
electrical cables nearby.
3.10 Automatic electronic welding equipment for metallic
parts
These generate frequent electrical arcs during operation,
for example for point welding of metallic sheets. The
electrical arcs are by nature unstable and intermitted,
and they behave like high frequency generators, more or
less the first generators used by Marconi in his first radio
transmissions.
Fig. 4 - Electromagnetic noise generated by a motor current at the
starting and stopping
starting stopping
motor
current
Fig. 5 - Electromagnetic noise generated by the alternate current of
a AC motor at the starting and stopping that occur when the
voltage value is high
AC voltage AC current
stopping
starting
FALSE ALARMS FROM ELECTROMAGNETIC EMISSIONS