Annex A: Glossary EFA-200/-300
A-2
Peak value (VECT PEAK)
The peak value of the magnetic flux density is calculated from the
variation in time B
x
(t) through B
z
(t) of the magnetic flux densities in the three
measurement axes.
The peak value is always dependent on the phase alignment of the
measured field component. This fact is taken into account in the vectorial
addition of the components.
The peak value of the electric field strength is calculated in the same
manner.
Averaging
Every measurement must be made over a sufficiently long period of time to
allow for variations in field strength over time. In accordance with the latest
standards and regulations, the EFA uses an observation period of precisely
one second.
This feature is of particular importance in certain situations:
Field exposure evaluation
Evaluation criteria that appear to be dependent on the variation with time of
the field are quoted in the safety standards.
Situation Effect
• Change of measurement range,
detection mode
• The RMS value rises to the final, correct
value within one second.
• Change in field at point of
measurement
• The RMS value is shown in accordance with
the standards.
• Measurement of pulsed signals • The displayed measurement value ≤ RMS
value within one pulse width.
Field type Evaluation
• Single-frequency fields • Derived limit for field strength
• Multiple-frequency fields • Summation formulae
• Pulsed fields • Variation in field with time
ˆ
B
ˆ
Max B
x
2
t() B
y
2
t() B
z
2
t()++
=
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