3-21
VIBXPER
T II 05.2012
Options
A1: Meas. setup parameters in the 'Overall values' & 'Advanced' tab
m
easurement
quantity
:
Fixed; selection is carried out via the measure-
ment icon. Exception: The measurement quantity can be changed
for the ‘Orbit’, ‘Phase’ and ‘Coastdown’ measurement tasks.
s
ample
frequency
(t
imewave
r
ecorder
):
The sample frequency for the
time signal defines the maximum upper frequency and influences
the maximum measurement time.
m
easurement
time
:
Duration of an individual measurement; this de-
pends on the lower frequency.
l
ower
/u
pper
f
requency
:
Frequency range of the vibration measure-
ment. The DC component of the signal can be recorded for the
'Vibration displacement' and 'User-defined' measurement tasks
(lower frequency = DC, see p. 5-30).
a
verage
type
/ n
o
.
of
measurements
:
Without averaging: Each single measurement is displayed.
Linear averaging: Single measurements are added and divided by
the number of averages.
Exponential averaging: The measurements are averaged expo-
nentially. The final individual measurements are more heavily
weighted.
Peak hold: Highest measurement value is displayed.
o
verlap
: Percentage by which consecutive measurements overlap; If
the overlap is 0%, the total measurement time is: number of aver-
ages x measurement time; the higher the overlap, the shorter the
total measurement time. For the runup / coastdown curve, the
number of usable measurements can be increased by selecting a
higher overlap.
t
ime
syhnchronous
averaging
(p
hase
, o
rBit
):
In this type of averaging,
the time signals of each individual rotation are averaged to reduce
non-synchronous components in the signal. The number of time
synchronous averages is either RPM-dependent (Auto), user-de-
fined or unrestricted:
‘Auto’: Number of averages is a function of the rotational speed*.
‘Manual’: Number of averages can be entered (max. 254).
‘Unrestricted’ (only in meas. setup for balancing): Each individual
measurement is averaged with the preceding individual measure-
ment. The longer the measurement takes, the more stabile the
final result. This averaging type is used for balancing runs. The
measurement must be stopped using the 'Enter' key.
During a phase measurement VIBXPERT calculates a phase vector
(amplitude and angle) from the time synchronous averaged signal.
This procedure is repeated several times in order to increase the
stability of the phase vector. The parameters for the phase averag-
ing correspond to the settings under "Average type / Number of
measurements' (see above).
* For example, time synchronous num-
ber of averages = 3, if speed>120 rpm.
Acceleration, low-speed
Содержание VIBXPERT II
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