BRUEL & KJAER System V - Reference Accelerometer

Reference Acce ler ometer
6.
Upper ra dial flexure
Magnetic Shie ld
_..,~- Moun ting holes for pro tecti ve ca n
Fram e
Moving element
ske let on· rib edge
Flexure mounting block
Lower radial fle xure
Tange
nt ial flexure
Split hub
~~~ _ ____ - __ Driver Coil
'-------1.-------"""'/---------- Drive connector to amplifier
272 (0 1
Fig. 6. 10. Calibration Head 4815
6.3.1 . Reference Accelerometer
The accelerometer built into the Type 4815 Head is a Standard Accelerometer Type
8305. It has been designed particularly for the precise ca libration of transducers by the
back-to-back comparison method. Careful design resulted in very low transverse and base
strain sensitivities, assuring a high degree of accuracy in comparison measurements .
Long term stabil ity and low sensitivity to temperature changes are obtained by using a
piezoelectric element of quartz. A sectional drawing of the accelerometer is shown in
Fig.6.11 . Construction is of the inverted single ended compression type, and a full dis-
cussion of its characteristics is contained in the "'Accelerometers"' Instruction Manual.
Fig. 6. 11. Cross-sectional view of the Type 8305 A ccelerometer
On a 4815, as delivered from the factory, the accelerometer is already mounted. How-
ever, in case it should be necessary at ariy time to remove the accelerometer from the
4815 Head, the following mounting instructions are included.
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