nardaHP-01

Analysis of static and
time-variable magnetic
fields
Field exposure evaluation according to current
standards and regulations such as Directive
2013/35/EU for workplaces
Frequency-selective and wideband
measurement of magnetic fields from 0 Hz to
1000 Hz
Non-directional (isotropic) measurement with
orthogonally arranged Hall sensors
Extremely wide measurement range from 10 µT
to 10 T (dynamic range 120 dB)
FFT spectrum analysis and time response
display
Narrow band filter for standard compliant
measurement in the range 0 Hz to 1 Hz
Optical interface for control by PC or NBM-550
(not yet supported)
Magnetometer HP-01
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APPLICATIONS
The Magnetometer HP-01 is a device for measuring static magnetic
fields and time-variable fields of frequencies up to 1000 Hz. Its main
application is in the measurement of high static fields with the aim of
ensuring the safety of personnel who have access to areas where such
fields are present. The possible risks are due to indirect effects, such as
the force exerted on ferromagnetic objects. As a consequence, hazards
can result from flying objects (projectile effect), or from the force exerted
on passive implants, or from functional impairments in active implants.
These must be identified and avoided. Risks can also occur due to
direct effects when the magnetic flux density is very high and movement
of the body within the field results in stimulation of sensory cells or nerve
cells. Exposure limit values are laid down in the ICNIRP Guidelines and
in the European Directive 2013/35/EU among other regulations. The
action  depend on the source of the hazard, ranging from relatively
low values (e.g. 0.5 mT for effects on active implants) up to very large
values of several Tesla. Typical areas where high fields are present are:
•  Magnetic resonance tomography (MRT)
•  Magnetic resonance spectroscopy (MRS)
•  Use and production of strong permanent magnets
such as lifting magnets
•  DC generators, particularly superconducting
•  DC motors, e.g. in railroads
•  Applications involving electric vehicles
•  Large industrial magnetic stirrers
•  Electrolysis used in the production of chlorine and aluminum
Figure 1: Particularly high static magnetic fields are
generated by magnetic resonance tomography (MRT)
Figure 2: Static magnetic fields are also present in DC
powered railroads
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FUNCTION
The exposure level limits and action levels specified in guidelines and
standards cover a wide range of values. This would usually mean that
several different measurement probes would be needed in order to
achieve the necessary measurement dynamic range. The HP-01 easily
covers all these applications with its built in Hall effect sensors, which
have an unusually wide overall dynamic range from 10 µT to more than
10 T. Additional measurement probes are not needed. The orthogonal
arrangement of the sensors in the tip of the probe wand ensures that the
three spatial axes are captured completely, guaranteeing an isotropic
(non-directional) measurement. The sensors are located approximately
7 mm below the tip of the wand and are indicated by a clearly visible
groove.
The HP-01 is much more than just a magnetometer probe, however. It
includes a very powerful FFT analyzer that allows signal analysis in both
the time and the frequency domains. The fast signal processing allows
detailed, highly accurate gap-free analysis of the frequency spectrum.
The results can be displayed as a live spectrum, as a spectrogram
versus time, or as a three-dimensional waterfall diagram.
The “DC – 1 Hz” operating mode is a further special feature that is
particularly suitable for standard-compliant measurements according to
human safety standards. The limit values are usually specified for static
fields and variable fields with frequencies of up to 1 Hz. A finite impulse
response (FIR) filter used in the HP-01 captures just these frequency
components. The measurement is made using a high sampling rate and
delivers the corresponding wideband value for the 0 Hz to 1 Hz range,
which is required in order to demonstrate compliance with the limit
values. If required, more extensive analysis in the sub-Hertz region can
be performed from the time domain display of the instantaneous values.
This would not be possible in this way from the FFT analysis.
The HP-01 is operated using the HP01-TS software supplied, which is
compatible with all Microsoft Windows ® based PCs running Windows 7
or above. An optical cable with USB adapter links the measuring device
to the PC. The measurement can therefore be controlled from a safe
distance of up to 10 m. This can be extended to 50 m with cables,
available as options.
Figure 4: Main window with display of measurement
parameters and numerical result
Figure 3: Connector side of HP-01 with tripod adapter
attached
Figure 5: Time response display of a sine wave signal
in the sub-Hertz range in DC-1Hz operating mode
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MEASUREMENTS USING A PC
The graphical user interface of the HP01-TS PC Software is arranged
very clearly and is easy to use. The main window (Figure 4) is displayed
when the program starts. The main settings such as measurement
range and frequency range are made in this window. The display area
continuously shows the numerical value of the magnetic flux density
measurement result, separately for the three spatial axes if required.
Click on the “Zero” button to trigger a zero adjustment that reduces
measurement uncertainty to a minimum. For this, the probe tip is placed
in the zero field chamber supplied, to exclude effects due to the earth’s
magnetic field or other fields. Three different modes enable selection of
frequency ranges for static fields (DC to 1 Hz), or for any single
frequency, or for band integration with settable frequency limits.
In addition to the numerical display of the measurement value, the time
response of the magnetic flux density can also be shown and evaluated
graphically. The graph shows the time response of the RMS value for
each of the three spatial axes and the isotropic total value. A constant
sine wave signal appears as a continuous horizontal line. In “DC - 1 Hz”
mode, the instantaneous value is shown instead of the RMS value, i.e. a
sine wave signal is also shown as a sine wave (Figure 5). This means
that even the frequency and amplitude of signal components below 1 Hz
can be determined.
FFT analysis represents the spectral distribution of the signal as an
amplitude spectrum (Figure 6). The spectrums are shown for the three
separate axes as well as for the isotropic total value. The frequency
range can be adapted in four stages by appropriate selection of the
“Span”. Two markers are provided to simplify result evaluation. It is also
possible to show the variation in the spectrum over time graphically,
either as a spectrogram (Figure 7) or as a waterfall diagram (Figure 8).
Figure 6: FFT analysis with display of amplitude
spectrum
Figure 7: FFT analysis with spectrogram display
Figure 8: FFT analysis with spectrum displayed as a
waterfall diagram
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SPECIFICATIONS  a
HP-01 Magnetometer
Frequency range  DC (0 Hz) to 1000 Hz
Probe type  Magnetic (B) field
Field sensor
Triaxial orthogonal Hall effect devices (temperature compensated)
Simultaneous triaxial acquisition
Sensor area approx. 0.6 mm x 0.6 mm (10 T), approx. 0.15 mm x 0.15 mm (60 mT)
Measurement
range  b
Auto Range  ±10 µT to ±10 T  (units: mT, T, G, kG)
60 mT  ±10 µT to ±60 mT  (units: mT, G)
10 T  ±0,010 T to ±10 T  (units: T, kG)
Overload  20 T
Dynamic range (after zeroing)  120 dB (Auto Range)
Resolution
60 mT range  100 nT (Span 20 Hz and 30 Hz), 1 µT (Span 100 Hz and 1000 Hz)
10 T range  100 µT (Span 20 Hz and 30 Hz), 1 mT (Span 100 Hz and 1000 Hz)
Displayed average noise level (DANL)  c 10 µT
Flatness of frequency response  0.5 dB (typ.)
Expanded measurement uncertainty  d ±1 %
Temperature response  0.05 % / °C typ. (@ 0 Hz referred to 23°C)
Temperature and humidity meter  Internal sensor, temperature: -20 °C to + 55 °C, humidity: 5 % to 95 % RH
DC MODE
Frequency range  0 Hz to 1 Hz
Filter  FIR filter, cut-off frequency 1.0 Hz (-3 dB)
Result display Numerical result display and time plot (instantaneous value vs. time)
Reading update time  67 ms
Result type Instantaneous value, maximum hold, averaging (linear)
FFT MODE
Spectrum analysis Real-time gapless  e FFT
SPAN  (selectable) 20 Hz  30 Hz  100 Hz  1000 Hz
Frequency range  0 – 20 Hz  0 – 30 Hz  0 – 100 Hz  0 – 1000 Hz
Resolution  0.2 Hz  0.3 Hz  1 Hz  3 Hz
RBW (-3 dB)  0.8 Hz  1.2 Hz  4 Hz  10 Hz
Result display
• Spectrum (full Span), spectrogram, waterfall (3D)
• Numerical broadband value with selectable cut-off frequencies, time plot (RMS vs. time)
• Single frequency and time plot (RMS)
Reading update time  < 350 ms
Result type  Actual value (RMS), maximum hold, averaging (RMS)
OPERATION
Measurement control and display
Via PC (not included) and supplied software HP01-TS
or via NBM-550 (this function is not yet available)
Supported operating systems  Microsoft Windows ® 7, 8/8.1, 10
Data interface  Serial optical interface (115200 Baud) with optical converter to USB
a Unless otherwise stated, these specifications apply for the reference condition: ambient temperature 23 °C, relative air humidity 50 %
b For each single axis. Positive and negative at static fields (DC)
c After zeroing. DANL is frequency and SPAN depending. The specified performance is referred to 0 Hz and SPAN 20 Hz
d At static fields (DC)
e Overlapping for Span 20 Hz, 30 Hz and 100 Hz
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® Names and Logo are registered trademarks of Narda Safety Test Solutions GmbH and L3 Communications Holdings, Inc. – Trade names are trademarks of the owners.
Narda Safety Test Solutions GmbH

HP-01 Magnetometer  Part number P/N
HP-01 Magnetometer Set DC-1kHz
Includes:
- HP-01 Basic Unit
- Zero Gauss Chamber
- AC/DC Battery Charger
- Cable, FO Duplex (1000 µm) RP-02, 10 m
- Cable, FO Duplex (1000 µm) RP-02, 25 cm
- O/E Converter USB, RP-02/USB
- Conical Tripod Support
- HP-01 / NBM Adapter
- Software CDROM including User’s Manual
- Certificate of Calibration
- Carrying Case
2405/101
OPTIonAL ACCESSORIES
Tripod, Non-Conductive, 1.65 m with Carrying Bag  2244/90.31
Tripod Extension, 0.50 m, Non-Conductive  2244/90.45
Cable, FO Duplex (1000 µm) RP-02, 2 m  2260/91.02
Cable, FO Duplex (1000 µm) RP-02, 5 m  2260/91.09
Cable, FO Duplex (1000 µm) RP-02, 20 m  2260/91.03
Cable, FO Duplex (1000 µm) RP-02, 50 m  2260/91.04