Atec Narda-EFA300 - Manual (Page 2)

30 narda Safety Test Solutions an communications company USA • Germany • Italy
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Electric and Magnetic Field Measurement
Operating Modes
Various standards and guidances take into account the fact
that signal shape plays a major role in determining the work-
place limit. For example, in Germany the employer’s liability
insurance association guideline on “Electromagnetic Fields”
specifies different evaluation guidelines for different field
shapes. Stationary sinusoidal and pulsed fields are differenti-
ated. Occasionally both the RMS value and the peak value,
(with proper phase) are critical for assessing exposure in the
low-frequency range.
This new generation of equipment greatly simplifies the
measurement process. Besides measuring the RMS and peak
values with the classic filter technique, the EFA-300 includes
the highly innovative mode known as STD (Shaped Time
Domain). With this new mode, both instruments achieve a
new standard in simple but reliable measurement, even in
very complex environments. A standard’s variation with
frequency can be automatically taken into account and
normalized. Field strength results are provided in a “Percent
of Standard.” Knowledge about the signal shape, frequency,
or frequency-dependent limits is no longer needed.
For individual frequency and field strength analysis, a very
fast FFT (Fast Fourier Transform) mode, which includes evalu-
ation of harmonics, is available as an option.
Field Strength Mode
Selective and Broadband Field Strength Measurements
In many practical applications, such as proximity to high-
voltage lines and transformer stations, this measurement is
simple and produces accurate results. If the field under test
has essentially a single frequency component, the broad-
band mode is the best choice. A broadband measurement of
the magnetic field in the frequency range from 5 Hz to 32 kHz
is made using the built-in isotropic probe. The Model EFA-300
can also be used to measure the electric field with the exter-
nal, cube-shaped E-field module.
For more precise analysis or multi-frequency fields, band pass
and band reject filters are available in the frequency range of
15 Hz to 2 kHz with user-editable filter lists. Operation is con-
figured to allow fast switching between common settings,
e.g., broadband and bandpass filter.
In broadband mode, the large, backlit display provides mea-
surement and frequency results simultaneously.
Two plug-in, B-field, probes extend the range of possibilities.
The small “sniffer” probe has a 3 cm diameter while the larger,
more sensitive probe, has a 100 cm 2 cross-sectional area.
Users can choose between RMS and peak value measurement
from less than 1 nT to 31.6 mT. The EFA-300 can also measure
the E-field from less than 1 V/m to 100 kV/m.
STD (Shaped Time Domain) Evaluation Mode
Innovative Technique for
Signal-Shape-Independent Field Measurements
In many situations, detailed knowledge of the field, test
equipment and other auxiliary conditions are necessary to
obtain insight into the degree of exposure when using tra-
ditional measurement equipment. Standardized evaluation
entails complicated analysis. However, the new and innova-
tive “Shaped Time Domain” technique simplifies the process.
The frequency dependency of standards is automatically
incorporated when using shaped-frequency-response mea-
surements. Suitable detectors are provided for measuring
the RMS and peak values. The analysis takes into account the
phase of the individual components.
The B- or E-field is measured over the entire frequency
range up to 32 kHz in real time and displayed as a Percent of
Standard.
STD analysis is not limited to specific signal shapes. Signals
with one or more frequencies and pulsed signals are no
problem. Pulsed signal measurements are possible since the
time-domain limits (e.g., those specified for selected pulsed
signals) can be directly converted into frequency-domain lim-
its. Proper evaluation in a personal safety context is achieved
quickly and reliably using the STD technique.
To evaluate the field, six limit curves (standards) are stored
in the device. A simple download procedure can be used to
update the instrument to cover new standards.
Spectrum FFT Mode
(Optional)
Spectrum analysis considerably simplifies the process of
quickly evaluating multi-frequency signals up to 32 kHz. All
spectral components are evaluated at once.
To provide a spectrum, the signal curve versus time is record-
ed via the probe and converted into the frequency domain
using a mathematical procedure known as “Fast Fourier
Transform.”
efa-300 field analyzer