Geokon 3900 Скачать руководство пользователя страница 5

 

1. INTRODUCTION 

 

The Model 3900 Embedment Strain Gauge is designed for the measurement of dynamic strains 

in concrete structures and soils. It comprises a full-bridge strain gauge proving ring element 

coupled in series with a tension spring which is stretched between two end flanges. An outer 

PVC tube sealed with O-rings provides a waterproof housing. The end flanges are embedded and 

move in accordance with the surrounding material. The voltage signals from the strain gauge are 

transmitted via cable to the readout location. 

 

The strain gauge can be read out by means of the Geokon Model 502 Readout Box or by a 

applying a 2 to 12 Volt excitation to the input leads and reading the corresponding millivolt 

output. The output at full range is approximately 3 mV/V. The standard wiring for use with the 

GK-502 readout box is configured to compensate for the use of long cables by the remote 

sensing of the input voltage at the sensor. A Thermistor is included inside the sensor to measure 

temperatures. This requires a cable with four shielded pairs of conductors. 

 

2. INSTALLATION 

 

The embedment gauge is delivered with the sensor set at an approximately midrange position 

ready for installment. The standard range is ± 2500 microstrains. (Other ranges are available). 

An initial test can be conducted by connecting the strain gauge to the GK-502 Readout Box or to 

a regulated voltage supply. Movement of the end flanges should produce a corresponding change 

in the gauge output. At no time should the end flanges be twisted or pulled beyond the range of 

the sensor as this could permanently damage the gauge. 

 

The gauge should be installed directly in the concrete or soil by hand. Large aggregate should be 

removed from the area immediately surrounding the sensor. The use of vibrators immediately 

next to the gauge should be avoided. The standard cable has a thick PVC jacket and can be 

placed directly in the concrete.  

 

3. TAKING READINGS 

 

Connect the ten-pin connector to the GK-502 readout box or connect the bare wires to a voltage 

supply and millivoltmeter as follows: 

 

Bendix Pin Circuit Label  Description  Geokon Purple Cable 

S- 

Bridge Output - 

White's Black 

P+ 

Bridge Exci 

Red 

P- 

Bridge Excitation - 

Red's Black 

S+ 

Bridge  

White 

NC 

No Connection 

NC 

Ground for shield 

Shield 

Thermistor 

Blue 

Thermistor 

Blue’s Black 

RS+ 

Remote Sense + 

Green 

RS- 

Remote Sense - 

Green's Black 

Table 1 - Input Connections 

Содержание 3900

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 2007 2019 by Geokon Doc REV E 04 30 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: ...ACTOR 4 APPENDIX A SPECIFICATIONS 5 APPENDIX B THERMISTOR TEMPERATURE DERIVATION 6 APPENDIX C TYPICAL CALIBRATION REPORT 7 FIGURES FIGURE 1 CIRCUIT DIAGRAM 2 FIGURE 2 TYPICAL CALIBRATION REPORT 7 TABLES TABLE 1 INPUT CONNECTIONS 1 TABLE 2 SPECIFICATIONS 5 TABLE 3 THERMISTOR RESISTANCE VERSUS TEMPERATURE 6 EQUATIONS EQUATION 1 DISPLACEMENT 3 EQUATION 2 STAIN CALCULATION WITH TEMPERATURE CORRECTION ...

Страница 5: ...vered with the sensor set at an approximately midrange position ready for installment The standard range is 2500 microstrains Other ranges are available An initial test can be conducted by connecting the strain gauge to the GK 502 Readout Box or to a regulated voltage supply Movement of the end flanges should produce a corresponding change in the gauge output At no time should the end flanges be t...

Страница 6: ...n Manual for additional information on the following instructions 1 Connect the embedment gauge to the readout box by means of the 10 pin input connector 2 Press the ON OFF button power switch to the ON position 3 Press the UNITS button until the UNITS displayed are mV V 4 Read the display and record 5 See the GK 502 Instruction Manual for further instructions ...

Страница 7: ... is the calibration factor in millimeters mV V or inches mV V as supplied on the Cal Sheet See Appendix C for a sample calibration report If a regulated power supply and a millivoltmeter are used then calculate the mV V by dividing the displayed millivolt output by the voltage input measured at the sensor using the remote signal leads Green and Green Black 4 2 Strain Calculation To calculate the s...

Страница 8: ...crostrains per C So for example using the GK 502 displaying mV V to take the readings and a standard eight inch long gauge where C is given in inches mV V the calculation for strain S corrected for temperature change T1 T0 measured in degrees Centigrade is S R1 R0 C 8 6 T1 T0 microstrain Equation 2 Stain Calculation with Temperature Correction Where C is given in mm mv v the equivalent equation is...

Страница 9: ...re Range 20 to 80 C 0 to 110 F Active Gauge Length2 203 mm Input Resistance 350Ω Output Resistance 350 Ω Excitation Voltage 2 to 15 V DC Maximum Excitation Voltage 30 V Cable Type Four twisted pair eight conductor 22 AWG Foil shield PVC jacket nominal OD 9 5 mm 0 375 Table 2 Specifications Notes Other ranges are available on request 2 Other gauge lengths available on request ...

Страница 10: ... 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 11: ...7 APPENDIX C TYPICAL CALIBRATION REPORT Figure 2 Typical Calibration Report ...

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