MMF VM30-H, Инструкция по эксплуатации, Страница: 19 / 58

After this choose the display mode “A(T)” (interval RMS, p.24).
Ignore the question “Save settings?” by pressing ESC.
Measurement is started by pressing the ESC key. This resets the averaged RMS values and the
timer to zero. The start of measurement must be after the start of vibration exposure. Otherwise
the result, averaged over the entire measuring period, would be wrong. The duration of
measurement shall represent a typical exposure interval. It should be at least 2 minutes. The
elapsed measuring time can be seen in the upper left display corner. A sufficiently long duration
of measuerement is reached if the measuring values do not change anymore.
If an overload should occur during measuerement, a message “OVERLOAD” will appear
instead of the measuring value (compare p. 29). The measuring result is invalid even if there
was only a short overload. For this reason the instrument will also display “Overload” in the
upper line as soon as an overload occurs on any channel. This message can be erased only by
pressing ESC.
If an overload is indicated, increase the measuring range for the respective channel, wait a few
seconds until the instrument has settled and start a new measurement by pressing ESC. The
measuring range must not be higher than necessary in order to provide maximum display
resolution.
After a sufficient duration of measurement you may save the result by pressing SAVE. The
vibration exposure must persist in the moment of saving. Please make sure that the instrument is
in the manual save mode. If necessary, select in the menu “2/8: Recording setup” the mode
“manually by SAVE key”. Otherwise the data logger will start after pressing the SAVE key.
You may also choose whether you like to save date and the time and a 20 characters comment
with the result. A comment text can be entered with the ◄▲▼► keys and OK.
If the vibration exposure is divided into different sections, measurements have to be performed
for each section.
Notice: You may simplify the setup of the VM30-H by means of pre-defined setups. Press the
▼ (LOAD) key to choose from 10 stored setups. In the original configuration setup no. 2
contains the settings for the interval RMS with the filters W
d
and W
k
for the seat surface and
setup no. 5 for the interval RMS with the filters W
d
and W
c
for the backrest (see p. 27).
5.3.3. Evaluation of Health Risks
The calculation of daily vibration exposure A(8) is based on the highest one of the three interval
RMS values (X/Y/Z) measured for each exposure section. The interval RMS value has to be
multiplied with the K factor depending on direction and weighting filter according to Table 1.
Example: For health risk evaluation with W
d
and W
k
the correction factors are K
X,Y
= 1.4 and
K
Z
= 1.
Notice: The interval RMS values displayed by the VM30-H do not include K factors.
The selected maximum interval RMS value multiplied with the appropriate K factor is inserted
as a
we
in Equation 1 or for more than one exposure sections as a
wi
in Equation 2.
If the interval RMS values of two axes have approximately the same magnitudes, daily
vibration exposure A(8) can also be calculated based on vibration total value Ahv. In this case
the K factors are taken into account for Ahv calculation by the VM30-H.
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