Kistler 8742A Series Instruction Manual Download Page 24

Shock Accelerometer 

Page 23 

 
002-096e-01.19 

 

 

8.3

 

Repairs 

Field  repair  is  not  possible.    Please  return  the  accelerometer  to  the 
factory together with a statement of problems encountered and unit 
serial  number.    Recalibration  is  recommended  when  returning  an 
accelerometer to the factory. Please contact the factory and obtain a 
return authorization number prior to return. 

   

8.4

 

Cleaning 

Clean the transducer with Isopropyl alcohol and lint-free paper wipes.  
Never  use  air-blast  to  clean  the  connector;  it  may  deposit  a  water 
vapor film.  Excess cyanoacrylate adhesive (e.g. Eastman 910, Loctite 
430,  etc.)  on  the  mounting  surface  may  be  removed  with 
dimethylformamide or acetone.  Refer to the adhesive manufacturer's 
product data for recommended removal agent. 

 

Do not us an abrasive on the base surface.  This can affect the flatness 
thereby reducing high frequency transmissibility. 

 

 

8.5

 

Calibration 

Calibration consists of the precise determination of the accelerometer 
sensitivity by direct comparison, at various frequencies, to a National 
Institute  of  Standards  and  Technology  (NIST)  traceable  standard 
accelerometer.    The  test  accelerometer  is  attached  to  the  top  of  the 
standard  in  a  "back-to-back"  configuration.    The  standard  and  test 
accelerometer are excited at appropriate frequencies and levels.  The 
resultant  amplitudes  of  both  accelerometers  are  then  compared  to 
determine if the test unit is within tolerance. 

Kistler  is  an  accredited  ISO  17025  Laboratory  and  offers  such 
calibration services.  A calibration certificate will be supplied showing 
calibration results from standards traceable to NIST.  

 

 

 

 

 

 

 

 

Summary of Contents for 8742A Series

Page 1: ...002 096e 01 19 Instruction Manual Shock Accelerometers Type 8742A...

Page 2: ...Shock Accelerometer Page 1 002 096e 01 19 Instruction Manual Shock Accelerometers Type 8742A CE Kistler Instrument 75 John Glenn Drive Amherst NY 14228 2171 Tel 716 691 5100...

Page 3: ...curing Cables 9 6 Operation 10 6 1 Powering 10 6 1 1 Using Built In Power Sources 10 6 1 2 Kistler Couplers 11 6 1 3 The Constant Current Power Supply Coupler 11 6 1 4 Sensor Power Up 14 6 1 5 Overloa...

Page 4: ...instructions carefully before installing and operating these instruments Kistler offers a wide selection of measuring instruments and comprehensive systems including Sensors for force pressure accele...

Page 5: ...ry area Keep the connector clean and covered when not in use Exercise care during cable connection Cable connector center pin should align with the female receptacle on the accelerometer Follow the re...

Page 6: ...ccelerometers are shear mode shock and vibration measuring instruments These units are intended for pyroshock testing metal to metal impact studies drop testing etc A self generating piezoelectric sen...

Page 7: ...material to produce an electric charge Since force is mass times acceleration from Newton s second law the charge produced is proportional to acceleration since m is constant This is represented by T...

Page 8: ...r 4 Cable 5 Readout or analysis equipment 6 Installation 6 1 General For proper operation of shock accelerometers care must be taken during the installation process Careful installation will result in...

Page 9: ...re that the base of the accelerometer makes full contact with the mounting surface See table 3 2 Completely clean the surface prior to mounting 3 Apply a thin coat of silicon grease to both the accele...

Page 10: ...1 2 minimum 28 UNF 0 22 5 6 0 42 10 7 Table 3 Mounting Surface Preparation 6 4 Securing Cables Figures 4 and 5 show the correct and incorrect ways for installing cables Allow a sufficient radius to en...

Page 11: ...7 1 1 Using Built In Power Sources Many FFT analyzers and vibration monitors are available with internal accelerometer power supplies Often identified as Constant Current Sources these internal power...

Page 12: ...Type 5114 plus front panel adjustable gain and filter provision 5148 16 channel rack mountable AC powered coupler with unity gain LEDs indicate circuit integrity Front panel BNC output connectors 5165...

Page 13: ...7 shows a schematic of a simple power supply coupler for shock accelerometers DC power is supplied from a 24 volt source such as a regulated power supply or batteries One advantage of the Piezotron s...

Page 14: ...Es 1 Eb Maximum negative amplitude Fs Eb 2 Where Fs Full scale output peak ES DC supply voltage sometimes called compliance voltage Eb bias voltage from calibration certificate Figure 8 Output Signal...

Page 15: ...ing range certain components will become non operational During this non operational state the amplifier components are protected from overload damage The amount of time required for recovery from an...

Page 16: ...he cable capacitance becomes significant thereby loading the Piezotron impedance converter If the current is not sufficient to charge the cable at an adequate rate high frequency distortion will be ex...

Page 17: ...creased the noise produced by the Piezotron circuit will also increase The miniature Piezotron amplifier will produce more heat as current is increased resulting in reduced life and reliability The sp...

Page 18: ...ed reference frequency over a specified bandwidth Shock accelerometers are specified with maximum variations of 5 to 10 Kistler uses the industry standard reference frequency of 100Hz Many users may b...

Page 19: ...ition will occur per the above equation which causes the sensitivity to increase with frequency It is desirable to have a uniform frequency response over the specified frequency range As can be seen F...

Page 20: ...cer The low frequency response of accelerometers is an electrical limitation The design of shock accelerometers is such that low frequency drift caused by temperature variations is virtually eliminate...

Page 21: ...ncy is the reciprocal of time The low frequency limit of shock accelerometers is defined as the point where the response is 5 also 10 where specified below the reference point 100 Hz The low frequency...

Page 22: ...by providing optimal low frequency response When using a simple coupler circuit Figure 7 with AC coupling a time constant equal to the product of the decoupling capacitor s C capacitance times the rea...

Page 23: ...onitor as follows A With the accelerometer connected check for a normal reading on the bias indicator normal should be around 11 VDC B If the bias reading is high 1 Disconnect the accelerometer at the...

Page 24: ...cturer s product data for recommended removal agent Do not us an abrasive on the base surface This can affect the flatness thereby reducing high frequency transmissibility 8 5 Calibration Calibration...

Page 25: ...Premium industrial cable connector 10 32 pos to BNC pos 1761sp x General purpose cable connector 10 32 pos to BNC pos 1762sp x General purpose cable connector 10 32 pos to BNC pos 1601Bsp BNC pos to...

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