Shielding
Measuring
In order to make a good shielding,
it is necessary that first a good measurement takes place.
Many think, that only the acquisition of a meter is enough for also being
able to measure correctly, but that is not so.
For good order I leave spectrum
analysers and EMV-measurement equipment here out of consideration.
There are meters for electrical
fields, which for good and proper functioning must be held at a certain distance
from the body.
Some must be hold close to the body; others must be hold with an outstretched
arm.
With certain meters,
it is a must that a good ground wire is attached.
With good meters, a good manual is implemented, but they must be read also.
Just let them lie somewhere does not hone the skills.
So, a lot of measuring technique
is necessary. It is always good upon reflecting what you are measuring in
the first place. It is ridiculous for measuring high frequency with a low
frequency meter. What fields do you want to measure?
What are the factors that can influence the working of the meter or the surroundings?
And did you calculate them in an sufficient way?
Is your meter reliable? There
are meters sold, which do not meet the specifications given by the manufacturer.
One thinks in measuring something, what in reality is not there at all, or
what cannot be measured by the meter, because the hardware can not perform
it, because the electronic parts are not adequate.
It can also happen, that a meter amplifies certain signals and weakens others, with the result that wrong conclusions are drawn.
In the frequency region up to
around 1 MHz we call the fields lowfrequent.
Everything above that
we call highfrequent (see Elektrosmog).
In lowfrequency fields we have
an electric- and a magnetic
alternating field, which each apart must be
measured.
The two different
measuring probes are quite often build into one apparatus, and is it possible
to alternate between the two modes by pressing a switch.
Notic, that with such meters,
for measuring the electrical field a ground
wire must be coupled.
For the magnetical field this
is not necessary, but there the
X-, Y- and
Z-axis must be measured. These three values must
be raised to a square, than added together,
and from this sum the root must be extracted
in order to determine the exact value of the magnetic alternating field.
In order to avoid running around
with a calculator, there are so-called 3D Teslameters;
they calculate that automatically. Just *point and read*.
Because there are quite many fluctuations in the power network,there are 3D
Tesla-meters with a Logger. They hold and store
these values over a longer period, and make it possible to study the peaks
and the fluctuations, and see at what points in time it happened.
Read on Measuring of highfrequency fields
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