Norsonic nor140, Instructional Manual

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193
Norsonic Nor140
Instruction Manual
193
Warm-up time
The warm-up time for the main instrument without
preamplifier/microphone is very short and the instru-
ment obtains the final accuracy as soon as the self-test
is made. Used with a preamplifier and microphone, this
time is prolonged due to the charging of the microphone
with the polarisation voltage. Normal sensitivity is reached
within one minute. Before a recalibration is attempted, at
least three minutes for warm-up is recommended.
Sensitivity for vibration
If the instrument is used under strong vibrational con-
ditions, it is recommended to use an extension cable
between the preamplifier and the instrument body.
The vibration will mainly affect the microphone, which
is most sensitive if the vibration is applied perpendicu-
lar to the diaphragm. Typical values are 55 dB to 65
dB for acceleration values of 1 ms
-2
perpendicular to
the diaphragm.
Sensitivity for magnetic fields
The maximum indication for exposure to magnetic field
of 80 A/m and any orientation is typically less than 20
dB.
Size and weight
Depth:
30 mm
Width:
75 mm
Length, excl. microphone/preamplifier:
210 mm
Length, incl. microphone/preamplifier:
292 mm
Weight incl. batteries:
410 g
Information for conformance testing
Reference Sound Pressure Level:
114.0 dB re
20 µPa. The reference frequency is 1000 Hz.
Reference Level Range:
The instrument has one
level range only.
Microphone Reference Point and Direction:
The
microphone reference point is the geometric centre
of the diaphragm of the microphone. The microphone
reference direction is from the microphone and along
the axis of rotational symmetry for the microphone and
preamplifier.
Battery voltage:
The instrument will automatically
switch off if the battery or external voltage is too low
for operation within the stated specifications. The max.
battery voltage for conformance testing is 4 ×1.6 V = 6.4 V.
Electromagnetic Compatibility:
When the instru-
ment is tested for conformance to electromagnetic
compatibility requirements, the instrument should be
in the measurement mode, as this normally will gen-
erate the highest levels of emissions. The highest
susceptibility is normally observed when the display
faces the principal direction of propagation for the
electromagnetic field.
For further information related to type approval
periodic verification, consult the factory.