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 Alstom M&D - PSP - 29 Nov 2011 - P 7

 ALSPA® Care : Vibration Sensors BasicsCase Mounted Transducers – Basic Designs

Basic design of two type of Case Mounted Transducer are:

 Acceleration Transducers –

- Compression Type

- Shear Type

Velocity Transducers –

- Moving coil sensor 

- A Piezoelectric accelerometer with integrating circuitMoving-coil

sensor 

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 Alstom M&D - PSP - 29 Nov 2011 - P 8

Shear Mode

 ALSPA® Care : Vibration Sensors BasicsPiezoelectric Accelerometers

 Accelerometers utilize two different techniques for generation of thevibration signal – resulting in two main mechanical models.

Compression Mode

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© ALSTOM 2011. All rights reserved. Information contained in this document is indicative only. No representation or warranty is given or should be relied on that it is complete or correct or will apply to anyparticular project. This will depend on the technical and commercial circumstances. It is provided without liability and is subject to change without notice. Reproduction, use or disclosure to third parties, withoutexpress written authority, is strictly prohibited.

 Alstom M&D - PSP - 29 Nov 2011 - P 9

Inner Compression constructionwith isolating tabs wired up to

circuit board

 ALSPA® Care : Vibration Sensors BasicsPiezoelectric Accelerometers

 All accelerometers have a frequency response with a high frequencyresonance.

Devices are typically utilizedup to a third of the natural

frequency

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 Alstom M&D - PSP - 29 Nov 2011 - P 10

Cut away view of Velomitor

 ALSPA® Care : Vibration Sensors BasicsVelocity Transducers

magnet

moving coil

case

mass

mounting stud

crystal

charge amp. &integration circuit

preload band

Velomitor Piezo-Velocity Sensor

Sensitive

 Axis

Traditional Moving-Coil Sensor