ENCARDIO RITE EDE-VXX User manual

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USERS’ MANUAL
DISPLACEMENT SENSOR
VIBRATING WIRE TYPE
MODEL EDE-VXX
ENCARDIO-RITE ELECTRONICS PVT. LTD.
A-7, Industrial Estate, Talkatora Road Lucknow, UP - 226011, India | P: [phone] | Email: [e-mail] | www.encardio.com
International: UAE | Qatar | Bahrain | Bhutan | Morocco | Europe | USA | UK
India: Lucknow | Delhi | Kolkata | Mumbai | Chennai | Bangalore | Hyderabad | J&K
Doc. # WI 6002.71 R04 | Sept 2018

www.encardio.com
TABLE OF CONTENTS
1INTRODUCTION 1
1.1 Types manufactured 1
1.2 Conventions used in this manual 1
1.3 How to use this manual 2
2VIBRATING WIRE DISPLACEMENT SENSOR 3
2.1 Operating principle 3
2.2 General Description 3
2.2.1 Encardio-rite model EDE-VXX-WP 4
2.2.2 Encardio-rite model EDE-VXX-RC 4
2.2.3 Encardio-rite model EDE-VXX-SC 4
2.3 Wiring 4
2.4 Taking readings with model EDI-54V vibrating wire indicator/logger 5
2.5 Sample test certificate 6
3CHECKING OF SENSOR AND INSTALLATION 7
3.1 Checking sensor before installation 7
3.2 Lightning protection 7
3.3 General precautions in cable installation 8
3.4 Initial reading 8
3.5 Installation 8
3.5.1 Encardio-rite model EDJ-40V vibrating wire crack/joint meter 9
4THERMISTOR - TEMPERATURE RESISTANCE CORRELATION 10
4.1 Thermistor - temperature resistance correlation 10
4.2 Measurement of temperature 11
4.3 Temperature correction 11
5TROUBLE SHOOTING 12
5.1 Symptom: displacement sensor reading unstable 12
5.2 Symptom: displacement sensor fails to read 12
6WARRANTY 13

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1 INTRODUCTION
The Encardio-rite model EDE-VXX linear displacement transducer incorporates a vibrating wire sensor. It
converts mechanical displacement to an electrical frequency output. This frequency output can be read or
logged by Encardio-rite model EDI-54V remote digital readout unit or Encardio-rite model EDAS-10 data
acquisition system.
The model EDE-VXX vibrating wire displacement transducer is used in geotechnical and structural
engineering applications where either it is difficult to take direct mechanical readings due to inaccessibility
or online data needs to be logged at a remote location. Some uses are:
to monitor rock mass or concrete displacement in single or multipoint borehole extensometers.
to monitor soil displacement in soil extensometers.
to monitor surface cracks in structures and rock mass (use Encardio-rite model EDJ-40V
vibrating wire crack/joint meter).
to monitor two or three axis displacement in joints of mass concrete (for uniaxial displacement
use Encardio-rite model EDJ-50V vibrating wire joint meter).
Vibrating wire displacement sensors have an advantage over conventional transducers like LVDT as the
former gives frequency, rather than a voltage, as output signal. The frequency signal can be transmitted
over long distances without any change in value caused by variations in cable resistance which can arise
from water penetration, temperature fluctuations, contact resistance or leakage to ground.
This factor, coupled with excellent zero stability and rugged design makes the model EDE-VXX
displacement transducer preferable for long-term measurements in adverse environments.
1.1 Types manufactured
Encardio-rite manufactures vibrating wire displacement sensors in three configurations:
EDE-VXX-WP: This is a water proof version and can withstand a water pressure upto 1 MPa
equivalent to 100 m of water column. It finds applications in areas exposed to water pressure.
EDE-VXX-RC: This has a cable coming out centrally from the back. It is for splash proof
applications but will withstand a water pressure of 0.2 MPa. It is mostly used in applications like
borehole extensometers and soil extensometers.
EDE-VXX-SC: It has M6 threads centrally on both ends of the sensor and so has a cable coming
out eccentrically from the back The sensor is suitable for applications upto a water pressure upto
0.4 MPa. It is mostly used in crack meters and biaxial/ triaxial joint meters.
1.2 Conventions used in this manual
WARNING! Warning messages calls attention to a procedure or practice, that if not properly followed
could possibly cause personal injury.
CAUTION: Caution messages calls attention to a procedure or practice, that if not properly followed may
result in loss of data or damage to equipment.
NOTE: Note contains important information and is set off from regular text to draw the users’
attention.

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1.3 How to use this manual
The users’ manual is intended to provide sufficient information for making optimum use of vibrating wire
displacement sensors for different applications.
To make the manual more useful we invite valuable comments and suggestions regarding any additions
or enhancements. We also request to please let us know of any errors that are found while going through
this manual.
NOTE: Installation personnel must have a background of good installation practices and knowledge
of the fundamentals of geotechnics. Novices may find it very difficult to carry on the
installation work. The intricacies involved in installation are such that even if a single
essential but apparently minor requirement is ignored or overlooked, the most reliable of
instruments will be rendered useless.
A lot of effort has gone in preparing this instruction manual. However the best of instruction
manuals cannot provide for each and every condition in the field, which may affect
performance of the instrument. Also, blindly following the instruction manual will not
guarantee success. Sometimes, depending upon field conditions, the installation personnel
will have to consciously depart from the written text and use their knowledge and common
sense to find the solution to a particular problem.
NOTE: This sensor is normally used to monitor site conditions and will record any change, even
though minor that may affect behaviour of the structure being monitored. Some of these
factors amongst others, are, seasonal weather changes, temperature, rain, barometric
pressure, earthquakes, nearby landslides, traffic, construction activity around site including
blasting, tides near sea coasts, fill levels, excavation, sequence of construction and changes
in personnel etc. These factors must always be observed and recorded as they help in
correlating data later on and also may give an early warning of potential danger or problems.
The manual is divided into a number of sections, each section containing a specific type of information.
The list given below tells you where to look for in this manual if you need some specific information. It is
however recommended that you read the manual from the beginning to the end to get a thorough grasp
of the subject. You will find a lot of unexpected information in the sections you feel you may skip.
For description of vibrating wire displacement sensor manufactured by Encardio-rite: See § 2 “Vibrating
wire displacement sensor”.
For test certificate: See § 3 “Sample test certificate”.
For installation: See § 4 “Checking of sensor and installation”.
For installation of crack/joint meter:See § 4.5.1 “Checking of sensor and installation”.
For complete operating procedure of Vibrating Wire readout unit EDI-54V: See Doc. # WI 6002.112’
For temperature effect: See § 5 “Thermistor - temperature resistance correlation “.
For trouble shooting: See § 6 “Trouble shooting “.
For Warranty:See § 7 “Warranty “.

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2 VIBRATING WIRE DISPLACEMENT SENSOR
2.1 Operating principle
Vibrating wire displacement sensor basically consists of a magnetic, high tensile strength stretched wire,
one end of which is anchored and other end fixed to a shaft through a precision coil spring that deflects in
some proportion to displacement. Any change in position of shaft, deflects the spring proportionally and
this in turn affects tension in the stretched wire. Thus any change in displacement, directly affects tension
in the wire and thus frequency of vibration.
The wire is plucked by a coil magnet. Proportionate to tension in wire, it resonates at a frequency ‘f’,
which can be determined as follows:
f = [σg/ρ]1/2/ 2l Hz
where σ = tension of wire in kg/cm2
g = 980 cm/sec2
ρ= density of wire in kg/cm3
l = length of wire in cm
The length of the wire in the displacement sensor is 5.5 cm. Consequently the formula can be reduced to:
f = 32 [σ]1/2 Hz
The resonant frequency, with which the wire vibrates, induces an alternating current in the coil magnet.
The displacement is proportional to square of frequency and the readout unit is able to display this directly
in engineering units.
2.2 General Description
The sensor body is of stainless steel construction. It has a shaft with M6 x 10 threads at the exposed end.
For monitoring displacement in any application, the shaft slides inside the sensor body with respect to the
latter. The shaft should never be rotated inside the sensor body as this will damage the transducer.
CAUTION: Never rotate shaft inside sensor body as this will damage the transducer. The shaft end is
provided with an alignment pin that sits inside an alignment slot on sensor body. Always
displace shaft axially while checking or installing sensor.
Each sensor is provided with a
thermistor for monitoring temperature.
Normally, no correction due to
temperature induced frequency
changes is required. However, if it is
necessary to make these corrections,
refer to data on zero shift due to
temperature changes provided in test
report (see § 3).
The displacement sensor is
manufactured in various capacities.
The three sensors EDE-VXX-WP,
EDE-VXX-RC and EDE-VXX-SC are
shown in the adjacent photograph.
WP
(water proof)
SC
(side cable)
RC
(rear cable)

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Dimensional details of the various types of vibrating wire displacement sensors manufactured are as follows:
2.2.1 Encardio-rite model EDE-VXX-WP
L±2
10
M6 (Both sides)
124
Ø19
Ø12.7
Figure 2.1 – Water proof sensor to withstand a water pressure upto 100 m of water column with
M6 threads on both sides for mounting
2.2.2 Encardio-rite model EDE-VXX-RC
L
Ø12.7
Ø19
±2
86 10
M6
Figure 2.2 – Sensor for splash proof applications with M6 x 10 threads on shaft. In applications
like borehole extensometer, the sensor body is clamped on Φ19
2.2.3 Encardio-rite model EDE-VXX-SC
L±2 10
M6 (Both sides)
Ø12.7
10
Ø29
Figure 2.3 – Water proof sensor to withstand a water pressure upto 40 m of water column with
M6 threads on both sides for mounting
Displacement mm
L mm
EDE-VXX-WP
EDE-VXX-RC
EDE-VXX-SC
15
X
X
207
25
260
222
222
50
330
292
292
100
460
422
422
150
590
552
X
2.3 Wiring
The sensor is provided with an integral 1 m long φ 4 mm four core PVC sheathed cable with cores in red,
black, green and white. Red and black cores are for frequency signal while green and white are for
temperature monitoring through a thermistor. In case specially ordered, PU sheathed cable can be
provided.

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2.4 Taking readings with model EDI-54V vibrating wire indicator/logger
The model EDI-54V vibrating wire indicator (figure
2.3) is a microprocessor-based read-out unit for use
with Encardio-rite’s range of vibrating wire sensors. It
can display the measured frequency in terms of time
period, frequency, frequency squared or the value of
measured parameter directly in proper engineering
units. It uses a smartphone with Android OS as
readout having a large display with a capacitive touch
screen which makes it easy to read the VW sensor.
The EDI-54V vibrating wire indicator can store cali-
bration coefficients from 10,000 vibrating wire sen-
sors so that the value of the measured parameter
from these sensors can be shown directly in proper engineering units. For transducers with built-in inter-
changeable thermistor, it can also display the temperature of the transducer directly in degree Centigrade.
The vibrating wire indicator has an internal non-volatile memory with sufficient capacity to store about
525,000 readings from any of the programmed sensors. Each reading is stamped with the date and time
the measurement was taken.
Refer instruction manual WI-6002.112 of model EDI-54V for entering the transducer calibration coeffi-
cients. The gage factor of the model EDE-VXX displacement sensor is given in the test certificate provid-
ed with every supply. The initial reading IR will be the actual reading in digits from the displacement sen-
sor after it is installed and properly fixed.
An internal 6 V 4 Ah rechargeable sealed maintenance-free battery is used to provide power to the vibrat-
ing wire indicator. A battery charger is provided to charge the internal battery which operates from 90 V to
270 V AC 50 or 60 Hz V AC mains. A fully discharged battery takes around 6 hours to get fully charged.
The indicator uses a smartphone as a readout that has its own internal sealed rechargeable Li-ion
maintenance battery as a power source. A separate battery charger/adapter unit for the smartphone, op-
erating from universal AC mains supply is supplied with each EDI-54V indicator unit.
The EDI-54V vibrating wire indicator is housed in an impact resistant plastic moulded housing with
weatherproof connectors for making connections to the vibrating wire transducer and the battery charger.
Fig 2.3 (a) – Vibrating wire indicator

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2.5 Sample test certificate
TEST CERTIFICATE
Instrument
:
Vibrating wire displacement sensor
Serial number
:
xxxxxxx
Date :
07.04.2018
Capacity
:
50 mm Temperature : 28°C
Input
Observed value
Average
End Point
Poly
Displacement
Up1
Up2
Fit
Fit
(mm) (Digit) (Digit) (Digit) (Digit) (mm) (mm)
0.00
2261.3
2250.4
2250.4
2255.9
0.00
0.00
10.00
3515.5
3489.3
3503.2
3509.4
10.10
10.01
20.00
4761.3
4736.0
4750.6
4755.9
20.15
20.01
30.00
5997.7
5977.4
5989.9
5993.8
30.13
29.99
40.00
7233.3
7215.3
7226.5
7229.9
40.09
40.00
50.00
8459.3
8459.3
8458.9
8459.1
50.00
50.00
Error (%FS)
0.30
0.02
Digit :
f ²/1000
Linear gage factor (G) :
8.0603E-03
mm/digit
Thermal factor (K) :0.011 mm/°C
Polynomial constants :
A=
1.5269E-08
B=
7.8979E-03
C=
-1.7899E+01
Displacement "D" is calculated with the following equation:
Linear
:
D(mm) =G(R1-R0)-K(T1-T0)
Polynomial
:
D(mm) = A(R1)² + B(R1) + C -K(T1-T0)-D0
R1 = current reading & R0 is initial reading in digit.
D0 = Initial reading in mm
Zero reference (initial position) in the field must be established by recording the initial reading R0 (digit) along with
temperature T0 (°C) just after installation.
Note :
Zero displacement reading given in above calibration chart is taken at around 3 mm from
mechanical zero, i.e. slider fully in
Pin configuration/wiring code: Red & black: Signal Green & white: Thermistor
CAUTION: Never rotate shaft of displacement sensor in respect to the outside body. This will permanently
damage the sensor. During checking pull or push shaft only axially. A pin has been provided at end of
displacement sensor that sits flush in a groove in sensor body.

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3 CHECKING OF SENSOR AND INSTALLATION
3.1 Checking sensor before installation
The cable from the sensor is four wired 1 m long. Red and black cores are for frequency signal while
green and white are for temperature monitoring through a thermistor.
Check the working of the sensor as follows:
The coil resistance measured by the digital multimeter should lie between 130-180 Ohm.
Determine resistance at the room temperature from thermistor temperature resistance chart in §
5. This resistance should be equal to that between the green and white wires. For example, in
case the room temperature is 25oC, this resistance would be 3,000 Ohm.
The resistance between any lead and the protective armour should be > 500 M Ohm.
Connect the sensor to the Encardio-rite model EDI-54V portable readout unit and switch it on.
The display will show something like:
Freq: 2230.8 Hz
where the actual figure will vary depending on the transducer connected to the indicator. This
initial reading on the portable readout unit should be stable.
A crude but a simple and very effective method of checking whether the displacement sensor is
responding to changes in displacement is as follows:
Shift the read-out unit display to the engineering unit mode. Using a scale, extend the
displacement sensor by about 5 mm. The reading in the digital readout unit should change by
around 5 mm. The change in reading ensures that the deformation produced by the displacement
is transmitted to the vibrating wire sensing element.
CAUTION: The displacement sensor is a delicate and sensitive instrument. It should be handled with
care. Twisting or applying too much force on the shaft with respect to the sensor body may
result in a zero shift or even permanent damage. Always displace shaft axially while
checking or installing sensor.
The shaft end is provided with an alignment pin that sits inside an alignment slot on sensor
body. When not in use or while tightening sensor against a shaft mounting object, keep the
pin engaged inside the slot to prevent any damage to the sensor by rotation of sensor
against shaft body.
3.2 Lightning protection
Lightning during thunderstorms can induce short spikes of sufficiently high electrical energy in the wires
connecting the vibrating wire sensor to the readout instrument that can damage the coils in the sensor
assembly. Some measure of lightning protection for the vibrating wire sensor is recommended if the
sensor is mounted in the field or in open areas and connected to the readout instrument through long
wires. However, these protection schemes will not protect the sensor against direct or near direct lightning
strikes. Lightning protection is generally not required if the connecting wire is very short, say only a few
meters in length, or both the sensor and the vibrating wire indicator is used inside a shielded structure,
e.g. a building.
The EDE-VXX vibrating wire strain gage is not available with any integral lightning protection component.
If lightning protection is desired one of the following options may be used:

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Surge arrestors like Gas Discharge Tubes (GDT) or TransZorbs(registered trademark of
General Semiconductor Industries) may be fixed to the sensor cable as near to the sensor as
possible and epoxy potted in place. The ground conductor would have to be connected to an
earthing stake or the steel structure itself.
If the vibrating wire displacement sensor is mounted close to a junction box or a multiplexer, the
surge arrestor component can be mounted in the junction box or the multiplexer box itself.
Encardio-rite can provide junction boxes and multiplexers with lightning protection installed as an
option (specify while ordering).
Lightning arrestor boards and enclosures are available from Encardio-rite, which can be installed
at the exit point of the structure being monitored. Consult the factory for additional information on
these or alternate lightning protection schemes.
3.3 General precautions in cable installation
Unless otherwise specified, each sensor is provided with 1 m cable attached. Cable may be extended
without affecting sensor reading or its long term performance. Always ensure a waterproof joint of
appropriate strength.
The procedure for laying of cables differs with individual installations. The cable should be routed in such
a way so as to minimize the possibility of damage due to moving equipment, debris or other causes. In
general:
Protect cable from damage by angular and sharp particles of material in which it is embedded.
In earth/rock embankments and backfill, cable must be protected from stretching due to
differential compaction of embankment. Cable must also be protected from damage by
compaction equipment.
The single most important factor leading to loss of worthwhile data from sensors is losing track of
identification of cable ends. Proper identification and marking of the cables is generally taken most
casually. Care should be taken to put an identification tag at the point where the cable comes out of the
structure such that cable identity is not lost if the cable gets cut or damaged. Route the cable properly to
the location where readings have to be taken, taking care that it is suitably protected. Gage and lead
wires must be protected from mechanical damage and from water.
Take care to keep cables as far away as possible from sources of electrical interference such as power
lines, welding equipment, motors, generators and transformers etc. To avoid picking up noise, cables should
never be buried or run along with AC power lines as this will cause problems in obtaining stable data.
3.4 Initial reading
Always carefully record initial displacement reading along with temperature at time of installation to serve
as a reference for determining subsequent deformation.
3.5 Installation
4.2.1 For using vibrating wire displacement sensor in borehole extensometer, refer to instruction
manual doc. # WI 6002.79 m
odel EDS-70V borehole extensometer system (bhe) with vibrating
wire sensors.
4.2.2 For using vibrating wire displacement sensor in soil extensometer, refer to method statement MS
0407
EDS- 92 soil extensometer.
4.2.3 For using vibrating wire displacement sensor for monitoring of cracks or joint openings on the
surface, refer to figures in § 4.5.1.