Geokon 6300 User manual

Instruction Manual
Model 6300
Vibrating Wire In-Place Inclinometer
No part of this instruction manual may be reproduced, by any 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 © 1995-2019 by Geokon®
(Doc Rev Q, 05/01/19)

Warranty Statement
Geokon warrants its products to be free of defects in materials and workmanship, under normal
use and service for a period of 13 months from date of purchase. If the unit should malfunction,
it must be returned to the factory for evaluation, freight prepaid. Upon examination by Geokon,
if the unit is found to be defective, it will be repaired or replaced at no charge. However, the
WARRANTY is VOID if the unit shows evidence of having been tampered with or shows
evidence of being damaged as a result of excessive corrosion or current, heat, moisture or
vibration, improper specification, misapplication, misuse or other operating conditions outside of
Geokon's control. Components which wear or which are damaged by misuse are not warranted.
This includes fuses and batteries.
Geokon manufactures scientific instruments whose misuse is potentially dangerous. The
instruments are intended to be installed and used only by qualified personnel. 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 of the installation or use of the product. The buyer's sole remedy for any breach of this
agreement by Geokon or any breach of any warranty by Geokon shall not exceed the purchase
price paid by the purchaser to Geokon for the unit or units, or equipment directly affected by
such breach. Under no circumstances will Geokon reimburse the claimant for loss incurred in
removing and/or reinstalling equipment.
Every precaution for accuracy has been taken in the preparation of manuals and/or software,
however, Geokon neither assumes responsibility for any omissions or errors that may appear nor
assumes liability for any damages or losses that result from the use of the products in accordance
with the information contained in the manual or software.

TABLE of CONTENTS
1. INTRODUCTION ...................................................................................................................................................1
1.1 TILT SENSOR CONSTRUCTION..............................................................................................................................2
2. INSTALLATION ....................................................................................................................................................3
2.1 PRELIMINARY TESTS............................................................................................................................................3
2.2 MODEL 6300 ASSEMBLY AND INSTALLATION .....................................................................................................3
2.2.1 Uniaxial System ..........................................................................................................................................4
2.2.2 Biaxial System.............................................................................................................................................5
2.3 FLUID DAMPING ..................................................................................................................................................7
2.4 SPLICING AND JUNCTION BOXES..........................................................................................................................7
3. TAKING READINGS.............................................................................................................................................8
3.1 GK-404 READOUT BOX.......................................................................................................................................8
3.1.1 Operating the GK-404 ................................................................................................................................8
3.2 GK-405 READOUT BOX.......................................................................................................................................9
3.2.1 Connecting Sensors.....................................................................................................................................9
3.2.2 Operating the GK-405 ................................................................................................................................9
3.3 GK-403 READOUT BOX (OBSOLETE MODEL)....................................................................................................10
3.3.1 Connecting Sensors...................................................................................................................................10
3.3.2 Operating the GK-403 ..............................................................................................................................10
3.4 MEASURING TEMPERATURES.............................................................................................................................10
4. DATA REDUCTION ............................................................................................................................................11
4.1 INCLINATION CALCULATION..............................................................................................................................11
4.2 TEMPERATURE CORRECTION .............................................................................................................................11
4.3 DEFLECTION CALCULATION ..............................................................................................................................12
4.4 ENVIRONMENTAL FACTORS...............................................................................................................................12
5. TROUBLESHOOTING........................................................................................................................................13
APPENDIX A. SPECIFICATIONS.........................................................................................................................14
A.1 VIBRATING WIRE TILT SENSOR ........................................................................................................................14
A.2 THERMISTOR (SEE APPENDIX BALSO) ..............................................................................................................14
APPENDIX B. THERMISTOR TEMPERATURE DERIVATION.....................................................................15
APPENDIX C. EXCITATION AND READOUT PARAMETERS......................................................................16
C.1 EXCITATION ......................................................................................................................................................16
C.2 EXCITATION FREQUENCY..................................................................................................................................16
C.3 OFFSET..............................................................................................................................................................16
APPENDIX D. ADDRESSABLE SYSTEMS..........................................................................................................17
APPENDIX E. TYPICAL CALIBRATION REPORT ..........................................................................................18

FIGURES
FIGURE 1-MODEL 6300 TILT SENSOR ASSEMBLY ........................................................................................................ 1
FIGURE 2-MODEL 6300 TILT SENSOR .......................................................................................................................... 2
FIGURE 3-TYPICAL INSTALLATION .............................................................................................................................. 3
FIGURE 4-BOTTOM WHEEL ASSEMBLY WITH SAFETY CABLE...................................................................................... 4
FIGURE 5-BIAXIAL SENSOR ASSEMBLY ........................................................................................................................ 5
FIGURE 6-BIAXIAL SENSOR ORIENTATION................................................................................................................... 5
FIGURE 7-TOP SUSPENSION.......................................................................................................................................... 6
FIGURE 8-LEMO CONNECTOR TO GK-404 ................................................................................................................... 8
FIGURE 9-LIVE READINGS –RAW READINGS............................................................................................................... 9
FIGURE 10 -DEFLECTION INTERVALS...........................................................................................................................12
FIGURE 11 -SAMPLE MODEL 6300 CALIBRATION REPORT...........................................................................................18
TABLES
TABLE 1-MODEL 6300 TILT SENSOR SPECIFICATIONS ................................................................................................14
TABLE 2-THERMISTOR RESISTANCE VERSUS TEMPERATURE .....................................................................................15
EQUATIONS
EQUATION 1-CALCULATION OF TILT (LINEAR)...........................................................................................................11
EQUATION 2-CALCULATION OF TILT (POLYNOMIAL)..................................................................................................11
EQUATION 3-TEMPERATURE CORRECTION .................................................................................................................11
EQUATION 4-HORIZONTAL DISPLACEMENT CALCULATION ........................................................................................12
EQUATION 5-RESISTANCE TO TEMPERATURE .............................................................................................................15

1
1. INTRODUCTION
The Geokon Model 6300 Vibrating Wire In-Place Inclinometer system is designed for long-term
monitoring of deformations in structures such as dams, embankments, foundation walls and the
like. The basic principle is the utilization of tilt sensors to make accurate measurement of
inclination, over segments, in boreholes drilled into the structure being studied. The continuous
nature of the instrument allows for very precise measurement of changes in the borehole profile
to be measured. The instrument is installed in standard grooved inclinometer casing (Figure 1).
Figure 1 - Model 6300 Tilt Sensor Assembly
Plan View
Sensor Housing
Stationary Wheel
Spring Tensioned Wheel
Connecting Tube
Inclinometer Casing
Instrument Cable

2
1.1 Tilt Sensor Construction
The sensor comprises a pendulous mass which is supported by a vibrating wire strain gauge and
an elastic hinge (Figure 2). The strain gauge senses the changes in force caused by rotation of the
center of gravity of the mass. The mass and sensor are enclosed in a waterproof housing which
includes components for connecting the sensor to wheel assemblies and/or other sensors. The
wheel assemblies centralize the sensors and allow the assembly to be lowered into the casing.
Swivel joints are included to prevent the wheel assemblies from running out of the casing
grooves due to spiral problems. Stainless steel tubing is used to connect the transducer and wheel
assemblies together, and the whole string is normally supported from the top of the casing.
Biaxial systems use two transducers mounted at 90°to each other.
To prevent damage during shipment the tilt sensors are locked in place by means of a
locking clamp screw. This slotted-head clamp screw must be removed and replaced by a
Phillips-head seal screw, (provided in the zip-lock bag), to render the tiltmeter operative.
Figure 2 - Model 6300 Tilt Sensor

3
2. INSTALLATION
2.1 Preliminary Tests
Prior to installation, the sensors need to be checked for proper
operation. Each tilt sensor is supplied with a calibration report
that shows the relationship between readout digits and
inclination. The tilt sensor electrical leads (usually the red and
black leads) are connected to a readout box (see Section 3 for
readout instructions) and the current reading compared to the
calibration readings. After backing-off the clamp screw three
full turns, carefully position the sensor against a vertical
surface and observe the reading. It will take a few seconds to
come to equilibrium and the sensor must be held in a steady
position. The readings should be within ±200 digits of the
factory reading, re-tighten the clamp screw three turns.
Note: Vibrating wire tilt sensors are shock sensitive and
severe shocks can cause a permanent offset or even break
the suspension. (The unit will not survive a two foot (0.5 m)
drop onto a hard surface). When transporting the tiltmeter
tighten the locking clamp screw.
Checks of electrical continuity can also be made using an
ohmmeter. Resistance between the gauge leads should be
approximately 180 Ω, ±10 ohms. Remember to add cable
resistance when checking (22 AWG stranded copper leads are
approximately 14.7Ω/1000' or 48.5Ω/km, multiply by two for
both directions). The resistance between the green and white
leads varies with temperature. Compare the measured
resistance and ambient temperature to the factors shown in
Table 2 in Appendix B. The resistance between any conductor
and the shield should exceed two megohm.
2.2 Model 6300 Assembly and Installation
1) Connect the safety cable to the bottom wheel assembly.
(See Figure 3.) This is strongly recommended. Not only
can it be used to retrieve the assembly in the event that one
of the joints breaks loose, but it is also very useful in
lowering the assembly into the casing. The alternative is to
hold the tube sections with vice-grips at the top of the
casing.
The bottom anchor is labeled and has no Universal joint,
just the swivel. The safety cable has a loop at its bottom
end which fits over the long bolt used to hold the bottom
anchor to the first tube section. This is shown in Figure 3.
The cable eyebolt is trapped between two nuts.
Figure 3 - Typical Installation
Top Support
Pr ot ect i v e Cap
Gage Cabl e
Incl inometer
Wheel A ssembl y
Sensor A ssembl y
Gage Tubing
Bottom Cap
Cable Connector
Casi ng

4
Figure 4 - Bottom Wheel Assembly with Safety Cable
2) Connect the first length of gauge tubing to the bottom wheel assembly. The length of tube is
shown in the table supplied with this manual. (In some cases, two tubes are joined together
by a special union.) Use the 10-32 screws and nuts, and a thread locking cement to make this
joint.
3) The next step is to attach the uniaxial or biaxial sensor assembly.
2.2.1 Uniaxial System
The uniaxial sensor is delivered unattached to its wheel assembly and should be attached
using the two 10-32 nuts and cap screws supplied. The tongue of the sensor fits inside the
slot of the wheel assembly with the orientation set such that the A+ direction marked on
the sensor is aligned on the same side as the fixed wheel on the wheel assembly. Tilts in
the positive direction yield increasing readings in digits.
Vibrating wire tilt sensors are shipped with a clamp screw holding the internal
pendulum mechanism so that it is not damaged in shipment. A label is attached to
each sensor emphasizing the importance of removing the slotted-head clamp screw
completely and replacing it with the Phillips-head seal screw taped to the sensor.
(Extra seal screws are provided in a zip-lock bag along with other accessories in case
some become lost). This is very important for the sensor to be able to respond to
tilting and remain waterproof.
The sensor and wheel assembly is now attached to the first tube section using a single
long 10-32 cap screw. (Use Loctite 222 on all threads.)

5
2.2.2 Biaxial System
The biaxial sensors are delivered unattached to the wheel assembly and to each other. The
upper sensor should be attached to the wheel assembly using the two 10-32 nuts and cap
screws supplied. The tongue of the sensor fits inside the slot of the wheel assembly with
the orientation set such that the A+ direction marked on the sensor is aligned on the same
side as the fixed wheel on the wheel assembly. (Tilts in the positive direction yield
increasing readings in digits).
The adaptor piece is now bolted to the bottom of the sensor using a single 10-32 cap
screw and thread locking compound (Loctite 222).
Figure 5 - Biaxial sensor assembly
Two short cap screws are used to attach the lower sensor via this adaptor with its positive
direction (Marked A+ on the sensor body) at 90° clockwise from the upper sensor (in plan
looking down the casing). This will be the B+ direction. See Figure 6.
Figure 6 - Biaxial Sensor Orientation
Note that there is some clearance around the bolt holes which will allow for some
manual alignment of the sensors (absolute alignment is not critical).
When the two sensors are connected, the lower one is joined to the previously prepared
gauge tube. Vibrating wire tilt sensors are shipped with a clamp screw holding the
internal pendulum mechanism so that it is not damaged in shipment. A label is
attached to each sensor emphasizing the importance of removing the slotted-head
clamp screw completely and replacing it with the Phillips-head seal screw taped to
the sensor. (Extra seal screws are provided in a zip-lock bag along with other
accessories in case some become lost). This is very important for the sensor to be
able to respond to tilting and remain waterproof.
Fixed Wheel
Instrument Cable
A+
B+
Instrument Cable

6
This assembly is now lowered into the borehole, using the safety cable, with the upper
assembly fixed wheel aligned in the so-called A+ direction. It is customary (and
recommended) to point the A+ direction in the same direction as the anticipated
movement, i.e., towards the excavation being monitored or down-slope in the case of
slope stability applications. Be sure that the lower wheel assembly and swivel are also
aligned this way.
While holding the assembly at the top of the casing, using either the safety cable or
vice grips on the tubing, the next segment with sensors, wheels and swivel are attached
and lowered in the same orientation. The system can become quite heavy and a clamp
of some sort may need to be used to hold the rods in place while being assembled. The
use of a winch to hold the safety cable can be a help. Note that the longer cables are on
reels to facilitate handling. Something like two little saw horses (or even folding chairs)
with a broom stick across them to act as an axle will allow the cable to spool off as
needed and provide a storage point for the rest of the cable.
The cables from the lower sensors should be taped or tie-wrapped to the assembly at
intervals to support them as the system is built up and lowered down the borehole.
Continue to add gauge tubing, sensors and wheel assemblies until the last sensor has
been attached to the upper wheel assembly, which is pre-assembled to the top
suspension (Figure 7). The Top suspension can then be lowered into position on the
casing. It is important that the end of the casing be cut square to prevent any side
pressure on the upper sensor wheel assembly.
Figure 7 - Top Suspension
After the sensor string has been lowered into position, the safety cable can be tied off around the
top of the casing and the signal cables can be run to the readout location and terminated or
otherwise fixed. Readings should be taken immediately after installation, but it is recommended
that the system be allowed to stabilize for a few hours before recording zero conditions.
For IPI strings that are going to measure only across a subsurface zone of interest and will not
reach the surface, the cross-piece of the top suspension is omitted and the IPI string is suspended
at the proper depth by a length of aircraft cable, attached to the eyebolt, and tied off at the top of
the casing.

7
2.3 Fluid Damping
The vibrating wire tilt sensor acts as a self-damping system when used in vibration free
environments. When external ground or structural vibrations exceed a certain threshold, the
pendulous mass will continue to "dither" and stable readings may not be possible. In such cases,
additional damping can be achieved by adding a viscous damping fluid to a small reservoir
contained in the sensor. A thin, wide "paddle" is connected to the mass and when the fluid is
added the pendulum is damped by the action of the paddle in the damping fluid.
Most in-place installations will not require this fluid. However, if the instrument gives unstable
outputs, or it is known that the structure is constantly vibrating, the fluid can be added. The fluid
is a high-viscosity silicone oil which must be injected into the sensor with a syringe.
The sensor must be held upright during the injection of the fluid and at all times following the
injection. This makes it necessary to perform this operation in the field. The following applies
for a typical in-place installation.
1) After connecting the sensor to the gauge tubing already in the casing, and after removal of
the clamping screw, use the syringe applied, first pull the piston from the syringe and
squeeze the silicone from the tube into the syringe. Replace the piston and start the silicone
oil out of the "needle" end.
2) Now, inject 2.00 cc into the hole in the sensor. Immediately following this operation, the seal
screw should be replaced in the sensor.
3) The sensor may now be lowered into the casing.
2.4 Splicing and Junction Boxes
Because the vibrating wire output signal is a frequency rather than current or voltage, variations
in cable resistance have little effect on gauge readings and, therefore, splicing of cables has little
effect and, in some case, may be beneficial. For example, if multiple sensors are installed in a
borehole, and the distance from the borehole to the terminal box or datalogger is great, a splice
could be made to connect the individual cables to a single multi-conductor cable. This
multiconductor cable would then be run to the readout station. For such installations it is
recommended that the transducer be supplied with enough cable to reach the top of the casing
plus enough extra to make splicing possible.
The cable used for making splices should be a high-quality twisted pair type with 100%
shielding (with integral shield drain wire). When splicing, it is very important that the shield
drain wires be spliced together! Splice kits recommended by Geokon incorporate casts placed
around the splice then filled with epoxy to waterproof the connections. When properly made, this
type of splice is equal or superior to the cable itself in strength and electrical properties. Contact
Geokon for splicing materials and additional cable splicing instructions.
Junction boxes and terminal boxes are available from Geokon for all types of applications. In
addition, portable readout equipment and datalogging hardware are available. Contact Geokon
for specific application information.

8
3. TAKING READINGS
3.1 GK-404 Readout Box
The Model GK-404 Vibrating Wire Readout is a portable, low-power, handheld unit that can run
continuously for more than 20 hours on two AA batteries. It is designed for the readout of all
Geokon vibrating wire gauges and transducers; and is capable of displaying the reading in either
digits, frequency (Hz), period (µs), or microstrain (µε). The GK-404 also displays the
temperature of the transducer (embedded thermistor) with a resolution of 0.1 °C.
3.1.1 Operating the GK-404
Before use, attach the flying leads to the GK-404 by aligning the red circle on the silver
“Lemo” connector of the flying leads with the red line on the top of the GK-404 (Figure
8). Insert the Lemo connector into the GK-404 until it locks into place.
Figure 8 - Lemo Connector to GK-404
Connect each of the clips on the leads to the matching colors of the 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 POS button. Displayed as a letter A through F.
•The current Reading: Set by the MODE button. Displayed as a numeric value
followed by the unit of measure.
•Temperature reading of the attached gauge in degrees Celsius.
Use the POS button to select position B and the MODE button to select Dg (digits).
(Other functions can be selected as described in the GK-404 Manual.)
The GK-404 will continue to take measurements and display readings until the unit is
turned off, either manually, or if enabled, by the Auto-Off timer. If the no reading
displays or the reading is unstable, see Section 5 for troubleshooting suggestions.
For further information, please see the GK-404 manual.

9
3.2 GK-405 Readout Box
The GK-405 Vibrating Wire Readout is made up of two components: The Readout Unit,
consisting of a Windows Mobile handheld PC running the GK-405 Vibrating Wire Readout
Application; and the GK-405 Remote Module, which is housed in a weatherproof enclosure and
connects to the vibrating wire gauge to be measured. The two components communicate
wirelessly. The Readout Unit can operate from the cradle of the Remote Module, or, if more
convenient, can be removed and operated up to 20 meters from the Remote Module.
3.2.1 Connecting Sensors
Connecting sensors with 10-pin connectors:
Align the grooves on the sensor connector (male), with the appropriate connector on the
readout (female connector labeled senor or load cell). Push the connector into place, and
then twist the outer ring of the male connector 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 Remote Module is waiting to connect to the handheld unit. Launch the GK-405
VWRA program by tapping on “Start” from the handheld PC’s main window, then
“Programs” then the GK-405 VWRA icon. After a few seconds, the blue light on the
Remote Module should stop flashing and remain lit. The Live Readings Window will be
displayed on the handheld PC. Choose display mode “B”. Figure 9 shows a typical
vibrating wire output in digits and thermistor output in degrees Celsius. If no reading
displays or the reading is unstable, see Section 5 for troubleshooting suggestions. For
further information, consult the GK-405 Instruction Manual.
Figure 9 - Live Readings – Raw Readings

10
3.3 GK-403 Readout Box (Obsolete Model)
The GK-403 can store gauge readings and apply calibration factors to convert readings to
engineering units. The following instructions explain taking gauge measurements using Mode
“B”. Consult the GK-403 Instruction Manual for additional information.
3.3.1 Connecting Sensors
Connecting sensors with 10-pin connectors:
Align the grooves on the sensor connector (male), with the appropriate connector on the
readout (female connector labeled senor or load cell). Push the connector into place, and
then twist the outer ring of the male connector 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).
3.3.2 Operating the GK-403
1) Turn the display selector to position “B”.
2) Turn the unit on.
3) The readout will display the vibrating wire output in digits. The last digit may change
one or two digits while reading.
4) The thermistor reading will be displayed above the gauge reading in degrees
centigrade.
5) 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 turn off automatically after approximately two minutes to
conserve power.
3.4 Measuring Temperatures
Each Vibrating tilt sensor is equipped with a thermistor for reading temperature. The thermistor
gives a varying resistance output as the temperature changes. Geokon readout boxes will read the
thermistor and display temperature in °C automatically. To read the thermistor using an
ohmmeter, complete the following:
1) Connect the ohmmeter to the two thermistor leads coming from the instrument. (Usually
white and green.) Since the resistance changes with temperature are large, the effect of cable
resistance is usually insignificant.
2) Look up the temperature for the measured resistance in Table 2 in Appendix B.

11
4. DATA REDUCTION
4.1 Inclination Calculation
Inclinations are measured in digits on Position B on the Geokon readout. The output of the VW
tilt sensor is proportional to the sine of the angle of tilt. For small angles θand sinθare the same,
so the relationship between output digits and the amount of tilting, (change of the angle of
inclination), ∆θ,is given by the equation:
∆θ = ∆sinθ= (R1−R0) G degrees tilt
Equation 1 - Calculation of Tilt (Linear)
Where;
R1 is the current reading in digits
Rois the initial reading in digits
G is the Linear Gauge Factor in degrees tilt/digit given on the calibration report supplied with the
sensor. (A sample calibration report is shown in Appendix E.)
The linear equation works very well for inclinations of less than four degrees. More than this and
the linearity errors start to increase beyond 0.5% FS. The error incurred by using the linear
equation is shown on the calibration chart.
For better accuracy at larger inclinations use the polynomial equation: This uses a second order
curve to approximate the sine curve.
θ= R2A + RB + C degrees tilt
Equation 2 - Calculation of Tilt (Polynomial)
Where A, B and C are the coefficients supplied on the calibration report. Calculate θ1by
substituting R = R1in the formula and then calculate θ0 by substituting R = R0then subtract to
find the difference ∆θ = (θ1- θ0).
4.2 Temperature Correction
The Model 6350 Tiltmeter has a slight temperature sensitivity on the order of -0.5 digit per °C
rise, i.e. the reading falls by 0.5 digits for every one °C rise of temperature. The temperature
correction is:
+0.5G(T1-T0) degrees tilt
Equation 3 - Temperature Correction
Normally, corrections are not applied for this small effect because the structure being monitored
usually is affected to a much greater degree. An important point to note, also, is that sudden
changes in temperature will cause both the structure and the Tiltmeter to undergo transitory
physical changes that will show up in the readings. The gauge temperature should always be
recorded for comparison, and efforts should be made to obtain readings when the instrument and
structure are at thermal equilibrium. The best time for this tends to be in the late evening or early
morning hours.

12
4.3 Deflection Calculation
Now, the change in reading must be converted to a lateral deflection. The lateral
deflection is defined as Lsin∆θ where L is the gauge length between pivot points
and ∆θ is the change in inclination (corrected for temperature) determined from
Equation 3.
The length L1, L2, L3,…. etc., can be calculated by adding 311 mm, (uniaxial
systems) or 524 mm, (biaxial system), to the individual lengths of tubing. This will
give the correct distance between pivot points.
The horizontal displacement profile can be constructed by using the cumulative sum
of the displacement starting with the bottom segment. Subsequent readings over
time will reveal changes in deflection, possible shear zones, etc. For example,
referring to Figure 10 and Equation 4.
D1= L1 ∆sinθ1
D2= L1 ∆sinθ1+ L2 ∆sinθ2
D3= L1 ∆sinθ1+ L2 ∆sinθ2 + L3 ∆sinθ3
D4= L1 ∆sinθ1+ L2 ∆sinθ2 + L3 ∆sinθ3+ L4 ∆sinθ4
D5= L1 ∆sinθ1+ L2 ∆sinθ2 + L3 ∆sinθ3+ L4 ∆sinθ4+L5 ∆sinθ5
Where, for small angles:
∆sinθ= (R1 −R0) G
Equation 4 - Horizontal Displacement Calculation
Although the system is designed for use with continuous segments and pivots, the
sensors can be installed without interconnecting tubing in standard, round tubing or
pipe using special friction anchoring. In those systems, the assumption is made that
the measured deflection occurs over the segment length and that L is the distance
between sensors.
4.4 Environmental Factors
Since the purpose of the inclinometer installation is to monitor site conditions,
factors that may affect these conditions should be observed and recorded. Seemingly
minor effects may have a real influence on the behavior of the structure being
monitored and may give an early indication of potential problems. Some of these
factors include, but are not limited to: blasting, rainfall, tidal or reservoir levels,
excavation and fill levels and sequences, traffic, temperature and barometric
changes, changes in personnel, nearby construction activities, seasonal changes, etc.
L
1
L
4
L
3
L
5
L
2
D5
Figure 10 -
Deflection Intervals

13
5. TROUBLESHOOTING
Maintenance and troubleshooting of the vibrating wire tilt sensors used in the Model 6300
Inclinometer are is confined to periodic checks of cable connections. The sensors are sealed and
there are no user-serviceable parts.
Consult the following list of problems and possible solutions should difficulties arise. Consult
the factory for additional troubleshooting help.
Symptom: Tilt Sensor 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? Most probable sources of electrical noise are
motors, generators and antennas. Make sure the shield drain wire is connected to ground
whether using a portable readout or datalogger. If using the GK-403, GK-404, or GK-405
connect the clip with the blue boot to the shield drain wire. (Green for the GK-401)
Does the readout work with another tilt sensor? If not, the readout may have a low battery or
be malfunctioning.
Symptom: Tilt Sensor Fails to Read:
Is the cable cut or crushed? This can be checked with an ohmmeter. Nominal resistance
between the two gauge leads (usually red and black leads) is 180Ω, ±10Ω. Remember to add
cable resistance when checking (22 AWG stranded copper leads are approximately
14.7Ω/1000' or 48.5Ω/km, multiply by two for both directions). If the resistance reads
infinite, or very high (megohms), a cut wire must be suspected. If the resistance reads very
low (<20Ω) a short in the cable is likely.
Does the readout or datalogger work with another tilt sensor? If not, the readout or datalogger
may be malfunctioning.
Symptom: Thermistor resistance is too high:
Is there an open circuit? Check all connections, terminals and plugs. If a cut is located in the
cable, splice according to instructions in Section 2.4.
Symptom: Thermistor resistance is too low:
Is there a short? Check all connections, terminals and plugs. If a short is located in the cable,
splice according to instructions in Section 2.4.
Water may have penetrated the interior of the tilt sensor. There is no remedial action.

14
APPENDIX A. SPECIFICATIONS
A.1 Vibrating Wire Tilt Sensor
Model:
6300
Range:¹
±10°
Resolution:²
8 arc seconds
Accuracy:³
±8 arc seconds
Linearity:4
±0.3% FSR
Thermal Zero Shift:
±4 arc seconds/°C
Operating
Temperature
-40 to +80° C
-40 to 175° F
Operating Frequency:
1400-3500 Hz
Coil Resistance:
180 Ω
Diameter:
1.250", 32 mm
Length:
7.375", 187 mm
Weight:
1.5 lbs., 0.7 kg.
Materials:
304 Stainless Steel
Electrical Cable:
Two twisted pair (four conductor) 22 AWG
Foil shield, PVC jacket, nominal OD=6.3 mm (0.250")
Table 1 - Model 6300 Tilt Sensor Specifications
Notes:
¹ Consult the factory for other ranges.
² Depends on readout equipment. With averaging techniques, it is possible to achieve one arc
second
³ Derived using 2nd order polynomial.
4The output from the sensor is proportional to the sine of the angle of tilt
A.2 Thermistor (see Appendix B also)
Range: -80 to +150 °C
Accuracy: ±0.5 °C