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10 

 

5. TROUBLESHOOTING 

 

Maintenance and troubleshooting of pressure cells is confined to periodic checks of cable 

connections and maintenance of terminals. Once installed, these instruments are usually 

inaccessible and remedial action is limited. 

Gauges should not be opened in the field.

 Should 

difficulties arise, consult the following list of problems and possible solutions. Return any faulty 

gauges to the factory. For additional troubleshooting and support contact Geokon. 

 

Symptom: Pressure Cell Readings are Unstable 

 

  Is the readout box position set correctly? If using a datalogger to record readings 

automatically are the swept frequency excitation settings correct? 

  Is there a source of electrical noise nearby? Likely candidates are generators, motors, arc 

welding equipment, high voltage lines, etc. If possible, move the instrument cable away from 

power lines and electrical equipment or install electronic filtering. 

   Make sure the shield drain wire is connected to ground whether using a portable readout or 

datalogger. Connect the shield drain wire to the readout using the blue clip. (Green for the  

GK-401.) 

 

  Does the readout work with another pressure cell? If not, it may have a low battery or 

possibly be malfunctioning. 

 

Symptom: Pressure Cell Fails to Read 

 

 

Is the cable cut or crushed? Check the resistance of the cable by connecting an ohmmeter to 

the gauge leads. Table 1 shows the expected resistance for the various wire combinations. 

Table 2 is provided for the user to enter the actual resistance found.  

 

Cable resistance is approximately 14.74

Ω

 per 1000' of 22 AWG wire. If the resistance is very 

high or infinite (megohms) the cable is probably broken or cut. If the resistance is very low (

<

20

Ω

) the gauge conductors may be shorted. If a cut or a short is located in the cable, splice 

according to the instructions in Section 2.3. 

 

  Does the readout or datalogger work with another gauge? If not, it may have a low battery or 

possibly be malfunctioning. 

 

Symptom: Thermistor resistance is too high 

 

 

Likely there is an open circuit. Check all connections, terminals, and plugs. If a cut is located 

in the cable, splice according to instructions in Section 2.3. 

 

Symptom: Thermistor resistance is too low 

 

 

Likely there is a short. Check all connections, terminals, and plugs. If a short is located in the 

cable, splice according to instructions in Section 2.3. 

 

 

Water may have penetrated the interior of the transducer. There is no remedial action. 

 

Содержание 4855

Страница 1: ... means without the written consent of Geokon The information contained herein is believed to be accurate and reliable However Geokon assumes no responsibility for errors omissions or misinterpretation The information herein is subject to change without notification Copyright 2003 2019 by Geokon Doc REV F 05 1 19 ...

Страница 2: ......

Страница 3: ...nnel There are no warranties except as stated herein There are no other warranties expressed or implied including but not limited to the implied warranties of merchantability and of fitness for a particular purpose Geokon is not responsible for any damages or losses caused to other equipment whether direct indirect incidental special or consequential which the purchaser may experience as a result ...

Страница 4: ......

Страница 5: ...EADOUT BOX 7 3 2 1 Connecting Sensors 7 3 2 2 Operating the GK 405 7 3 3 GK 403 READOUT BOX OBSOLETE MODEL 8 3 3 1 Connecting Sensors 8 3 3 2 Operating the GK 403 8 3 4 MEASURING TEMPERATURES 8 4 DATA REDUCTION 9 4 1 PRESSURE CALCULATION 9 4 2 TEMPERATURE CORRECTION 9 4 3 BAROMETRIC CORRECTION 9 5 TROUBLESHOOTING 10 APPENDIX A SPECIFICATIONS 12 A 1 PRESSURE CELLS 12 A 2 THERMISTOR SEE APPENDIX B A...

Страница 6: ...READINGS RAW READINGS 7 TABLES TABLE 1 SAMPLE RESISTANCE 11 TABLE 2 RESISTANCE WORK SHEET 11 TABLE 3 SPECIFICATIONS 12 TABLE 4 THERMISTOR RESISTANCE VERSUS TEMPERATURE 13 EQUATIONS EQUATION 1 DIGITS CALCULATION 9 EQUATION 2 CONVERT DIGITS TO PRESSURE 9 EQUATION 3 TEMPERATURE CORRECTION 9 EQUATION 4 RESISTANCE TO TEMPERATURE 13 ...

Страница 7: ...ressure cell is directly equivalent to the end bearing load 1 2 Pile Tip Pressure Cell Design and Construction The basic cell is manufactured to be close to the diameter of the pile It is comprised of two circular stainless steel plates welded together around their periphery leaving a thin space between the plates filled with de aired hydraulic oil This oil filled space is connected via a pressure...

Страница 8: ...a space between it and the surrounding concrete which if allowed to remain might prevent the transmission of pressures from the concrete to the cell To overcome this provision is made so that the cell can be inflated until it comes back into perfect contact with the concrete on both surfaces This re inflation is performed from the surface through a hydraulic line operating through a check valve An...

Страница 9: ...n and white should be approximately 3000Ω at 25 C see Table 4 in Appendix B and between any conductor and the shield should exceed 20 megohm 2 2 Pressure Cell Installation The short pieces of threaded re bar are screwed into the lugs welded to the bottom plate of the pressures cell A depression is excavated in the ground and lined with sand The shape of the depression should match the profile of t...

Страница 10: ...ake readings of pressure and temperature at regular intervals throughout the installation process It should be possible to monitor the pressure of the wet concrete as it is poured Allow the concrete set up and cool to a temperature close to ambient It may be observed that there is a drop in cell pressure from the value observed with the wet cement when the hole was filled Connect the cell re infla...

Страница 11: ...erefore splicing of cables has no ill effects and in some cases may in fact be beneficial The cable used for making splices should be a high quality twisted pair type with 100 shielding and an integral shield drain wire When splicing it is very important that the shield drain wires be spliced together Always maintain polarity by connecting color to color Splice kits recommended by Geokon incorpora...

Страница 12: ... sensor conductors with blue representing the shield bare To turn the GK 404 on press the ON OFF button on the front panel of the unit The initial startup screen will be displayed After approximately one second the GK 404 will start taking readings and display them based on the settings of the POS and MODE buttons The unit display from left to right is as follows The current Position Set by the PO...

Страница 13: ...ctor until it locks into place Connecting Sensors with Bare Leads Attach the GK 403 2 flying leads to the bare leads of a Geokon vibrating wire sensor by connecting each of the clips on the leads to the matching colors of the sensor conductors with blue representing the shield bare 3 2 2 Operating the GK 405 Press the button labeled POWER ON A blue light will begin blinking signifying that the Rem...

Страница 14: ...t may change one or two digits while reading The thermistor reading will be displayed above the gauge reading in degrees centigrade 4 Press the Store button to record the value displayed If the no reading displays or the reading is unstable see Section 5 for troubleshooting suggestions The unit will automatically turn itself off after approximately two minutes to conserve power 3 4 Measuring Tempe...

Страница 15: ...ration Sheet 4 2 Temperature Correction The vibrating wire sensor is relatively insensitive to temperature fluctuations and usually the effect of temperature is insignificant and can be ignored But if desired correction for temperature effects on the sensor can be made using the factors supplied on the calibration sheet and Equation 3 Also there are spurious temperature effects caused by the misma...

Страница 16: ...s the readout work with another pressure cell If not it may have a low battery or possibly be malfunctioning Symptom Pressure Cell Fails to Read Is the cable cut or crushed Check the resistance of the cable by connecting an ohmmeter to the gauge leads Table 1 shows the expected resistance for the various wire combinations Table 2 is provided for the user to enter the actual resistance found Cable ...

Страница 17: ... infinite infinite infinite White infinite infinite N A 3000Ω at 25 C infinite Green infinite infinite 3000Ω at 25 C N A infinite Shield infinite infinite infinite infinite N A Table 1 Sample Resistance Vibrating Wire Sensor Lead Grid SENSOR NAME Red Black White Green Shield Red Black White Green Shield Table 2 Resistance Work Sheet ...

Страница 18: ... 1 FSR optional Operating Temperature 30 to 70 C Frequency range 1400 3500 Hz Dimensions Diameter to suit the pile Thickness approximately 50 mm Material 303 304 Stainless Steel Electrical Cable Two twisted pair four conductor 22 AWG Foil shield PVC jacket nominal OD 6 3 mm 0 250 Table 3 Specifications Consult the factory for other sizes or options available A 2 Thermistor see Appendix B also Rang...

Страница 19: ... 2 83 107 9 123 77 66K 36 8006 4 1363 44 331 5 84 105 2 124 72 81K 35 7618 5 1310 45 321 2 85 102 5 125 68 30K 34 7252 6 1260 46 311 3 86 99 9 126 64 09K 33 6905 7 1212 47 301 7 87 97 3 127 60 17K 32 6576 8 1167 48 292 4 88 94 9 128 56 51K 31 6265 9 1123 49 283 5 89 92 5 129 53 10K 30 5971 10 1081 50 274 9 90 90 2 130 49 91K 29 5692 11 1040 51 266 6 91 87 9 131 46 94K 28 5427 12 1002 52 258 6 92 8...

Страница 20: ...the bottom and a steel belt around the periphery adjacent to the bottom These features require that tapped lugs be welded on the upper plate of the cell at specific locations to match corresponding holes drilled in the cross piece When the cage has been lifted to a vertical position it is lowered onto the cell The bottom of the cage should be guide by at least two people to prevent it from twistin...

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