©
Brüel & Kjaer Vibro
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08/2020
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C105519.001/v03
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Page 19 of 32
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Brüel & Kjaer Vibro
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Instruction 8315
Application
EN
UNRESTRICTED DOCUMENT
2 Application
The sensor 8315 is an uni-axial charge type acceleration sensor. In connection with the external
charge amplifier 2661 it is used for the measurement of vibration acceleration on rotating machinery
like turbines, pumps, compressors, etc.
3 Usage
The 8315 acceleration sensors are working according to the piezoelectric shear principle. Inside the
sensor, a piezo ceramic and an internal seismic mass form an oscillatory spring-mass damping
system. As soon as vibrations are induced into the system, the mass exerts a changing force onto the
ceramic. Due to the piezo effect, electric charges occur, which are proportional to the acceleration.
4 Mounting
As a general rule, the following applies:
The acceleration sensor is an additional parasitic mass which loads the object on which it is mounted
and this changes the vibration behaviour if it is too large.
The weight of the acceleration sensor should always be lower at least by a factor ten than the weight
of the object onto which it is mounted.
The sensor requires a friction-locked, contact resonance-free, rigid mounting to the object, particularly
for measurements at high frequencies.
