Vibration Measurements - BRUEL & KJAER 4292 Instructions And Applications

Once the vibration measurement system has been calibrated turn the
AMPLITUDE control to its "Off" position and remove the accelerometer
from the vibration table, first disconnecting the lead connected to its output
socket before unscrewing it from the table. This prevents the accelerometer
and its connection cable from being damaged.
Note: After the system has been calibrated, avoid touching the SENSI-
TIVITY control of the 4292 as otherwise the calibration will be lost.
3.3. VIBRATION MEASUREMENTS
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1. Carry out the calibration procedure described in section 3.2.
2. Mount the accelerometer as rigidly as possible onto the measurement
object. This can be done using one of the methods described in the
instruction manual for the accelerometer.
3. Taking care to avoid cable whip, connect the output of the acceler-
ometer to the 10- 32 NF preamplifier INPUT socket of the 4292
using one of the Miniature Accelerometer cables Type AO 0037,
AO 0038, AO 0051, AO 0052, or AO 0500. The standard input
socket to the preamplifier may also be used when the Coaxial Adapter
Type JP 0028 is employed.
4. Keep the 4292 as far away as possible from the vibration environment
and any other unrequired influences.
5. Set the INTEG RATION SWITCH for the required type of measure-
ments i.e. acceleration velocity, or displacement. In the "Velocity" or:
"Displacement" modes of this switch a lower limiting frequency ( 1 Hz
for "3 m/sec", 10 Hz for "0.3 m/sec" and 100 Hz for "0.03 m/sec"
velocity ranges, or 1Hz for "1000 mm", 3Hz for "100 mm", 10Hz
for "10 mm", 30Hz for "1 mm", 100Hz for "0.1 mm" and 300Hz
for "0.01 mm" displacement ranges) which is equal to or less than the
lowest measurement frequency of interest should be selected. This
ensures that signals with frequency components equal to, or greater
than the lowest frequency of interest are correctly integrated.
6. Keeping the OUTPUT SECTION ATTENUATOR (or RANGE
MULTIPLIER) switch in its "x1" position as far as possible, adjust
the INPUT SECTION ATTENUATOR (or METER RANGE) switch
to obtain a suitable meter indication without overload on the indicat-
ing instrument.