Atec EFA300 User Manual

Electric and Magnetic Field Measurement

5 Hz to 32 kHz

EFA-300 Field Analyzer

For Isotropic Measurement of Magnetic and Electric Fields

Evaluation of Field Exposure Compared to ♦
Major Standards and Guidances (selectable)

Shaped Time Domain (STD) – an innovative ♦
technique for signal-shape-independent
field measurements

Fast Fourier Transform (FFT) Spectral Analysis ♦
Peak Value Measurement with Proper Phase ♦
Large-Capacity Data Storage ♦
Remote Control ♦

Applications

The EFA-300 is an ideal field analyzer for measuring magnetic and electric fields in
the workplace and in public spaces. It is designed for professional users in the power
industry, at municipal utilities, by insurers, and for health and safety professionals in
industry. In the low frequency range, it handles virtually any required measurement,
simply and precisely. This instrument provides field analysis using an FFT computa­tion in addition to measuring magnetic and electric fields. The innovative STD mode
opens up further application areas. With this new mode the measurement results for
magnetic and electric field strength are displayed as a Percent of Standard, regardless
of the signal shape. This mode enables fast and reliable measurement and evalua­tion of the typical fields where complex, non-sinusoidal signals are common, e.g., in
industrial applications that use resistance welding. Resistance welding issues surface
in the traditional 50/60 Hz systems as well as in the newer medium-frequency switch­ing units.

Basic Operation

The EFA-300 has a built-in, isotropic, magnetic field probe. Optional external probes
can be used to handle other applications. For example, an isotropic B-field probe with
high sensitivity and a large (100 cm2) cross-sectional area is available for the standard­ized measurement of dissimilar magnetic fields.

For measurements in hard-to-reach places, a miniature 3 cm diameter B-field “sniffer”
probe is available.

The EFA-300 includes a cubic-shaped, isotropic, E-field module. This E-field module
contains both the sensor and circuitry that allows it to be operated independent of
the base unit. The base instrument, or a computer with the EFA-TS remote software,
can be used to read results in real-time and control the functions of the module. In the
data-logging mode, the E-field module can be operated independently. Stored data
can be read and analyzed at a later date using a computer and the EFA-TS software.
The major advantage of operating the E-field module remotely is that it greatly reduc­es the influence of the human body on the electric field you are trying to measure.

narda Safety Test Solutions an communications company USA • Germany • Italy

USA TEL: [phone] • FAX: [phone] • E-MAIL: [e-mail] • www.narda-sts.us

29

Electric and Magnetic Field Measurement

EFA-300 Field Analyzer

Operating Modes

Various standards and guidances take into account the fact
that signal shape plays a major role in determining the work­place 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 differenti­ated. 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 evalu­ation of harmonics, is available as an option.

Field Strength Mode

Selective and Broadband Field Strength Measurements

In many practical applications, such as proximity to high­voltage lines and transformer stations, this measurement is
simple and produces accurate results. If the field under test
has essentially a single frequency component, the broad­band 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 exter­nal, 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 con­figured to allow fast switching between common settings,
e.g., broadband and bandpass filter.

In broadband mode, the large, backlit display provides mea­surement 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

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.

2

cross-sectional area.

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 tra­ditional measurement equipment. Standardized evaluation
entails complicated analysis. However, the new and innova­tive “Shaped Time Domain” technique simplifies the process.

The frequency dependency of standards is automatically
incorporated when using shaped-frequency-response mea­surements. 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 lim­its. 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 record­ed via the probe and converted into the frequency domain
using a mathematical procedure known as “Fast Fourier
Transform.”

30

narda Safety Test Solutions an communications company USA • Germany • Italy

USA TEL: [phone] • FAX: [phone] • E-MAIL: [e-mail] • www.narda-sts.us

Electric and Magnetic Field Measurement

The EFA-300 is so powerful that even transient events ranging
up to 2 kHz can be analyzed in real time.

Evaluation is supported by graphics to clearly show the fre­quency spectrum and by cursor functions with frequency
and level indications. The RMS and peak values of the nine
most significant frequency components are easy to read.

You can also use this mode to normalize the display to a given
standard. The measured value is then displayed relative to its
associated standard. In visual terms, the frequency-depen­dent standard becomes a straight line. This makes it easy to
determine the relevancy of each spectral component.

EFA-300 Field Analyzer

Analyze the data and provide a graphic representation of •
the results to support the user in the preparation of mea­surement reports

FEATURES

Windows® interface to configure the instrument and/or to •
control it remotely.

Graphic representation of data stored in the internal mem-•
ory of the instrument or in a file:

Line diagrams show field strength or Percent of −
Standard versus time. Can be used in real time.

Display of spectrum −

−

Bar graph of harmonics
2D-views with import possibility: background maps −

for Matrix-data sets
Graphic tools – zoom, marker, set-up for scale, color/ −

thickness of lines, etc.

Additional Analysis Functions: •

Statistics – mean and maximum values, histogram, −
and number of values over a defined threshold

Peak list for spectrums −

Export Functions•

Data sets as ASCII-files −
Graphic screen into the clipboard −

Harmonic Analysis Mode

(Included with Spectrum FFT Mode)

This mode enables fast, convenient evaluation of the harmon­ic spectrum. A table lists the field strengths of the measured
fundamental frequency along with up to 8 harmonics.

This feature is very useful for a “hands-off” verification of pow­er quality (“Quality of Service”) in addition to occupational
safety applications.

Remote And Data Analysis
Software EFA-TS

This optional software is used to:

Provide remote control of the field analyzer •
and data readout

Download the data stored in the device•
Save acquired data on the computer •

MINIMUM SYSTEM REQUIREMENTS

Microsoft® Windows® 95 or Higher −
Windows NT® 4.0 or Higher −
Pentium Processor −
Min. 4 MB RAM −
Graphic card VGA 640/480, 256 colors −
CD-ROM

−

narda Safety Test Solutions an communications company USA • Germany • Italy

USA TEL: [phone] • FAX: [phone] • E-MAIL: [e-mail] • www.narda-sts.us

31