BRUEL & KJAER 2203 - Calibration Using the Accelerometer Calibrator Type 4291

Input Stage
,---- •=?-===~= ---------------.1
Adaptor
JJ 2615
~ Li~ --A~ .... ·~~~
Adaptor
JJ 2614
Adaptor
DB 0962
Adaptor
JP 0028
Integrator
ZR 0020
Fig. 3. 3. Connection of accelerometer
Accelerometer
760572
3.5.2. Calibration using Accelerometer Calibrator Type 4291
The portable battery-operated Accelerometer Calibrator Type 4291 generates a vibration
level of 1 g peak (0, 707 g RMS) at 500 rad s-1 (79,6 Hz). The calibration procedure is
as
follows:
1. Mount the accelerometer on the 4291 (see the 4291 Instruction Manual), and con-
nect it to the 2203 using one of the methods shown in Fig.3.3. If an Integrator is
used,
set it to the required position ("Ace.", "Vel.", or "Disp.").
2. Pull the METER SWITCH out, and set it to "Batt." to check the batteries; then set it
to "Fast" and "Lin.". (The instrument warm-up time is 20 s.)
3.
Set the 4291 to "Internal Gen." and adjust the ACC. LEVEL so that the lower scale
of the 4291 meter indicates the mass of the accelerometer (given on its calibration
chart) . The accelerometer is now vibrating at exactly 1 g peak.
4. Set the ATTENUATORS of the 2203 to give the meter needle a deflection of at least
1/3 full scale with the OUTPUT ATTENUATOR (transparent) as far clockwise as pos-
sible, and turn the ADJ. potentiometer with a small screwdriver until the needle lies
on "+ 7,0" dB.
5 .
Note the attenuator setting inside the red lines, and add 1 0 dB. This gives the zero
reference value in dB (Z) corresponding to 1 g RMS, or any of the following vibration
reference amplitudes (R) (which are equivalent to 1 g RMS at 79,6 Hz) to which the
2203 is now calibrated depending on the Integrator setting:
Acceleration:
Velocity:
Displacement:
9,81 ms-2 RMS
1 9,6 X 1 o-3 ms-1 RMS
39,2 X 1 o-
6
m RMS
( 1 g RMS = 386 in s-2 RMS)
(7,71 x 10-1 in s-1 RMS)
( 1 , 54 X 1 o-3 in R M s)
This adjustment will need to be made for each parameter to be measured. It is thus
easier to calibrate for, and to make all measurements of, one parameter first, then
recalibrate for another parameter and make measurements, if possible, rather than
switch from one to another.
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