Calibration Of Measur€Tnent System - BRUEL & KJAER 4292 Instructions And Applications

2. The measuring arrangement is placed some distance away from the
measuring point. The 7 core cable connecting the PREAMP. plug to
the 4292 may be extended using the Extension Cables Type AO 0027
(length 3m), Type AO 0028 (10m) or Type AO 0029 (30m). If a
greater cable length is required then several extension cables may be
connected together. The influence of capacitive loading on the high
frequency response of the 4292 when different lengths of extension
cable are employed is shown in F ig.5.6.
3.2. CALIBRAtiON OF MEASURING SYSTEM
To calibrate the measuring arrangement for a vibration acceleration level
of 1 g peak (9.81 m/sec
2 )
the built in vibration table of the 4292 may be
used as follows:
1. Set the 4292 on a flat, rigid horizontal surface and connect its PRE-
AMP. PLUG to the seven pin input socket of the indicating instru-
ment to be used for measurements. See section 3. 1.
2. Using a 10- 32 NF mounting stud, screw the accelerometer hand-
tight (mounting torque 18 kgcm or 15 lb in) onto the shaker table. If
miniature accelerometers are used they should be fitted using a 3 mm
mounting stud with the 3 mm to 10-32 NF Adapter Type DB 1425.
In this case the max. torque is 10 kg.cm or 8.51b in.
3. Set the controls on the indicating instrument for linear operation
using its PREAMP. (or CONDENSER MICROPHONE) input, with
METER FUNCTIONS of "Peak Slow", or "RMS Fast" selected. Set
the INPUT and OUTPUT SECTION ATTENUATORS or the METER
RANGE and RANGE MULTIPLIER switches to "1 00 mV" and "x 1"
respectively for calibration using accelerometers with sensitivities
greater than 15mV/g, or to "10mV" and "x 1" respectively for
accelerometers with sensitivities less than 15 mV /g.
4. On the 4292 set the INTEG RATION SWITCH to its "Accel.
-10 m/sec
2 "
mode and adjust the AMPLITUDE control to obtain a
small meter deflection on the indicating instrument. If necessary
adjust the SENSITIVITY control.
5. Using the RESONANCE control on the rear panel of the 4292 adjust
the mechanical resonance of the shaker ·system so that the meter
indication peaks at a maximum value. If the ball mounted in the table
9