Geosense TP-1 User manual

V1.0 Oct 2020
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THERMISTOR PROBE
& STRING

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CONTENTS
Page
1.0 INTRODUCTION 3
1.1 General Description 3
1.2 Theory of operation 4
2.0 CONFORMITY 5
3.0 MARKINGS 6
4.0 DELIVERY 7
4.1 Packaging 7
4.2 Handling 7
4.3 Inspection 7
4.4 Storage 7
5.0 INSTALLATION 8
6.0 DATA HANDLING 9
6.1 Taking readings 9
6.1.1 Portable Readouts 9
6.1.2 Data loggers 9
6.2 Data reduction 10
7.0 TROUBLESHOOTING 11
8.0 SPECIFICATION 12
9.0 SPARE PARTS 12
10.0 RETURN OF GOODS 13
11.0 LIMITED WARRANTY 14

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It is VITAL that personnel responsible for the
installation and use of Therrmistors READ and
UNDERSTAND the manual, prior to working with the
equipment.
1.1 General Description
Thermistors provide accurate and reliable long-term temperature measurements and are
used widely in the extremely harsh environments found within Geotechnical monitoring.
They are available in two types:
Probe – A single point sensor mounted within a PVC or stainless steel housing which is
attached to a cable length.
String – A series of sensors mounted along a multi-core cable which provide a
temperature profile and is manufactured to customer requirements in terms of the number
and spacing of each sensor.
Applications such as, but not limited to measuring temperature in the following :-
Concrete (particularly RCC dams)
Soil
Tundra
Rock
Ice caps
Glaciers
Landfills
Particular features of Geosense® Thermistors are:-
Fast response
High accuracy
Reliable long term performance
Suitable for demanding environments
Waterproof to IP68 (10 bar)
(Continued on page 4)
1.0 INTRODUCTION
This manual is intended for all users of Thermistor instruments manufactured by
Geosense® and provides information on their principle, installation, operation and
maintenance.

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1.2 Theory of Operation
The NTC (negative temperature coefficient ) 3K thermistor sensor has a resistance that
decreases with increasing temperature and with a coefficient >4%/ºC allows it to detect
very small changes in temperature.
They have a non-linear output that is represented by the Steinhart–Hart equation.
T= (1 / (A + B (LnR) + C(LnR) 3)) –273.2
Where: T = Temperature in degrees Centigrade
LnR= Natural log of Thermistor resistance in ohms
Readings can be made with a wide range of readout units including the VWR-1, MP12
which display the reading directly in degrees Celsius or resistance Ohms or by an
ohmmeter in combination with look-up tables.
Readings can also be automated using an automatic data acquisition unit such as a Linx
Logger, WI-SOS VW Node, GeoLogger CR Series
(Continued from page 3)

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2.0 CONFORMITY
Geosense Ltd
Nova House
Rougham Industrial Estate
Rougham, Bury St Edmunds
IP30 9ND
Email: [email protected].uk, Web: www.geosense.co.uk.
Declaration of Conformity
We Geosense® Ltd at above address declare under our sole responsibility that the Geosense® products
detailed below to which this declaration relates complies with protection requirements of the following
harmonized EU Directives:-
The Electromagnetic Compatibility Directive 2014/30/EU
Restriction on the use of certain Hazardous Substances RoHS2 2017/2102/EU
Waste electrical & electronic equipment WEEE 2012/19/EU
Equipment description Thermistors, Thermistor Strings
Make/Brand Geosense
Model Numbers TP-1, TP-2, TS-1, TS-2, TS-3, TS-4, TS-5, TS-6
Compliance has been assessed with reference to the following harmonised standard:
EN 61326-1:2013 Electrical equipment for measurement, control and laboratory use.
EMC requirements. General requirements.
A technical file for this equipment is retained at the above address.
Martin Clegg
Director
October 2020

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3.0 MARKINGS
Geosense® Thermistors are labelled with the following information:-
Product Name
Product Type
Individual Serial Number
Manufacturers Name & Address
CE Mark
Markings on Geosense® Thermistors varies depending on whether it is a Probe Type or a Thermistor
String.
The Probe Type only has a label on the end of the able identifying its reference S/N - Label A
The Thermistor String has an additional label - label B
Label A Label B

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4.3 Inspection / functionality check readings
It is important to check all the equipment in the shipment as soon as possible after
taking delivery and well before installation is to be carried out. Check that all the
components detailed on the documents are included in the shipment. Check that the
equipment has not been physically damaged.
CHECK the Thermistor readings against the approximate environmental temperature
on arrival to ensure they have not been damaged during transportation. This is a
basic ‘out of the box’ functional check.
4.0 DELIVERY
This section should be read by all users of Thermistors manufactured by
Geosense® .
4.2 Handling
Whilst they are a robust devices, Thermistors piezometers are precision measuring
instruments. They, and their associated equipment, should always be handled with
care during transportation, storage and installation.
Once the shipment has been inspected (see below), it is recommended that
Thermistors remain in their original packaging for storage or onward transportation.
Cable should also be handled with care. Do not allow it to be damaged by sharp
edges, rocks for example, and do not exert force on the cable as this may damage
the internal conductors and could render an installation useless.
4.1 Packaging
Thermistors are packed for transportation to site. Packaging is suitably robust to
allow normal handling by transportation companies. Inappropriate handling
techniques may cause damage to the packaging and the enclosed equipment. The
packaging should be carefully inspected upon delivery and any damage MUST be
reported to both the transportation company and Geosense®.
4.4 Storage
All equipment should be stored in an environment that is protected from direct
sunlight. It is recommended that cables be stored in a dry environment to prevent
moisture migrating along inside them in the event of prolonged submersion of
exposed conductors.
Storage areas should be free from rodents as they have been known to damage
connecting cables.
No other special requirements are needed for medium or long-term storage although
temperature limits should be considered when storing or transporting associated
components, such as readout equipment.

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5.0 INSTALLATION
Geosense Thermistor Strings are manufactured to specific customer requirements with the
following variables:-
• Length of cable to the first Thermistor
• Number of Thermistors
• Spacing between each Thermistor
THERMISTOR LOCATION
ALONG CABLE COLOUR CODING
1GREEN WHITE
2BLACK RED
3BLACK WHITE
4BLACK GREEN
5BLACK BLUE
6BLACK YELLOW
7BLACK BROWN
8BLACK ORANGE
9RED WHITE
10 RED GREEN
11 RED BLUE
12 RED YELLOW
13 RED BROWN
14 RED ORANGE
15 GREEN WHITE
16 GREEN BLUE
17 GREEN YELLOW
18 GREEN BROWN
19 GREEN ORANGE
20 WHITE BLUE
21 WHITE YELLOW
22 WHITE BROWN
23 WHITE ORANGE
24 BLUE YELLOW
25 BLUE BROWN
They should be installed in accordance with the specific project requirement.
It is therefore important that the correct reference is made & recorded for each sensor.
Below is the colour coding for multiple Thermistors up to a total of twenty six with
Thermistor number one being the nearest to the bare ended cable and from where readings
should be taken.

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6.0 DATA HANDLING
The function of an instrument is to provide useful and reliable
data. Accurate recording and handling of the data is essential
if it is to be of any value.
6.1 Taking readings
6.1.1 Portable Readouts
Geosense® offer a range of readout and data logging options which can be used to
read Thermistors. Specific operation manuals are supplied with each readout device.
Below is a brief, step-by-step procedure for use with
the Geosense® VWR1 portable readout.
1. Connect signal cables from the Thermistor to
the GREEN & WHITE terminals
2. Press the ‘On/Off’ button to switch the unit on.
Press it again to acquire a reading from the
connected instrument.
3. The readout displays the temperature reading in
both resistance (Ohms) and degrees C.
For more details see the VWR-1 readout
manual.
4. Press and hold down the On/Off’ button to
switch the unit off.
NAN IS DISPLAYED AS NO VW SENSOR IS CONNECTED
6.1.2 Data Loggers
A number of data loggers are available to automatically excite, interrogate and record
the reading from Thermistors. These include the GeoLogger CR Series and
GeoLogger Linx

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6.2 Data Reduction
Where a readout such as the VWR-1 is used the data is obtained directly as degrees
Celsius together with the corresponding resistance reading in Ohms.
If another type of readout such as a Multi Meter is used the reading will only be in
Ohms and therefore to convert to degrees Celsius the Steinhart & Hart look up table
is required (see below)
Ohms Temp Ohms Temp Ohms Temp Ohms Temp Ohms Temp
201.1K -50 16.60K -10 2417 30 525.4 70 153.2 110
187.3K -49 15.72K -92317 31 507.8 71 149.0 111
174.5K -48 14.90K -82221 32 490.9 72 145.0 112
162.7K -47 14.12K -72130 33 474.7 73 141.1 113
151.7K -46 13.39K -62042 34 459.0 74 137.2 114
141.6K -45 12.70K -51959 35 444.0 75 133.6 115
132.2K -44 12.05K -41880 36 429.5 76 130.0 116
123.5K -43 11.44K -31805 37 415.6 77 126.5 117
115.4K -42 10.86K -21733 38 402.2 78 123.2 118
107.9K -41 10.31K -11664 39 389.3 79 119.9 119
101.0K -40 9796 01598 40 376.9 80 116.8 120
94.48K -39 9310 11535 41 364.9 81 113.8 121
88.46K -38 8851 21475 42 353.4 82 110.8 122
82.87K -37 8417 31418 43 342.2 83 107.9 123
77.66K -36 8006 41363 44 331.5 84 105.2 124
72.81K -35 7618 51310 45 321.2 85 102.5 125
68.30K -34 7252 61260 46 311.3 86 99.9 126
64.09K -33 6905 71212 47 301.7 87 97.3 127
60.17K -32 6576 81167 48 292.4 88 94.9 128
56.51K -31 6265 91123 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 85.7 132
44.16K -27 5177 13 965.0 53 250.9 93 83.6 133
41.56K -26 4939 14 929.6 54 243.4 94 81.6 134
39.13K -25 4714 15 895.8 55 236.2 95 79.6 135
36.86K -24 4500 16 863.3 56 229.3 96 77.6 136
34.73K -23 4297 17 832.2 57 222.6 97 75.8 137
32.74K -22 4105 18 802.3 58 216.1 98 73.9 138
30.87K -21 3922 19 773.7 59 209.8 99 72.2 139
29.13K -20 3748 20 746.3 60 203.8 100 70.4 140
27.49K -19 3583 21 719.9 61 197.9 101 68.8 141
25.95K -18 3426 22 694.7 62 192.2 102 67.1 142
24.51K -17 3277 23 670.4 63 186.8 103 65.5 143
23.16K -16 3135 24 647.1 64 181.5 104 64.0 144
21.89K -15 3000 25 624.7 65 176.4 105 62.5 145
20.70K -14 2872 26 603.3 66 171.4 106 61.1 146
19.58K -13 2750 27 582.6 67 166.7 107 59.6 147
18.52K -12 2633 28 562.8 68 162.0 108 58.3 148
17.53K -11 2523 29 543.7 69 157.6 109 56.8 149
Resistance versus temperature table for 3K @25°C Thermistor

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7.0 TROUBLESHOOTING
RESISTANCE DIAGNOSTICS
Where damage to a sensor or cable is suspected this guide illustrates the way in which
simple resistance checks can be taken to identify the possible cause of the problem.
Resistance checks can be made with most types of multi-meter which are readily
available in the market.
RESISTANCE OF THE THERMISTOR
STEP 1
Set the range to 20kΩ (or Ω if using a multi-meter which has automatic ranging).
STEP 2
Connect the T+ (green) conductor to the red lead on the multi-meter and the T- (white)
to the black lead on the multi-meter.
The readings will be dependent on the temperature as below:-
10°C ~ 5.971kΩ (5971Ω)
15°C ~ 4.714kΩ (4714Ω)
20°C ~ 3.478kΩ (3478Ω)
25°C ~ 3.000kΩ (3000Ω)
PLEASE REFER TO THE THERMISTOR LOOK UP TABLE ON THE NEXT PAGE

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8.0 SPECIFICATION
* Other temperature ranges available on request
** Readout dependent
9.0 SPARE PARTS
As a Thermistor is a sealed unit, it is neither serviceable nor does it contain any
replaceable parts.
PROBE
Model TP-1 TP-2
Temperature range* -50 to +150 ºC -50 to +150 ºC
Accuracy ± 0.2 ºC ± 0.2 ºC
Resolution** 0.1 ºC 0.1 ºC
Housing PVC Stainless steel
Housing diameter (mm) 31 16
Housing length (mm) 85 85
Cable diameter (mm) 7 7
Cable Type 900 - VW Sensor with Foil Screen & Drain Wire String
STRINGS
Model TS-1 TS-2 TS-3 TS-4 TS-5 TS-6
Temp range* -50 to +150 ºC
Accuracy ± 0.2 ºC
Resolution** 0.1 ºC
Points 1-2 3-4 5-7 8-10 11-15 16-25
Cable diameter 7 8.9 9.8 11.4 12.5 14.8
Cable Type 910 - Multi-Core with Foil Screen & Drain Wire
Housing diameter (mm) 19, 31 19, 31 31 31 31 31
Housing length (mm) 85 85 85 85 85 85

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10.0 RETURN OF GOODS
10.1 Returns procedure
If goods are to be returned for either service/repair or warranty, the customer should
contact Geosense® for a Returns Authorisation Number, request a Returned
Equipment Report Form QF034 and, where applicable, a Returned Goods Health and
Safety Clearance Form QF038 prior to shipment. Numbers must be clearly marked on
the outside of the shipment.
Complete the Returned Equipment Report Form QF034, including as much detail as
possible, and enclose it with the returned goods.
10.2 Inspection & estimate
It is the policy of Geosense® that an estimate is provided to the customer prior to any
repair being carried out. A set charge for inspecting the equipment and providing an
estimate is also chargeable.
10.3 Warranty Claim
(See Limited Warranty Conditions)
This covers defects which arise as a result of a failure in design or manufacturing. It is a
condition of the warranty that the Thermistor must be installed and used in accordance
with the manufacturer’s instructions and has not been subject to misuse.
In order to make a warranty claim, contact Geosense® and request a Returned
Equipment Report Form QF034. Tick the warranty claim box and return the form with
the goods as above. You will then be contacted and informed whether your warranty
claim is valid.
10.4 Packaging and Carriage
All used goods shipped to the factory must be sealed inside a clean plastic bag and
packed in a suitable carton. If the original packaging is not available, Geosense® should
be contacted for advice. Geosense® will not be responsible for damage resulting from
inadequate returns packaging or contamination under any circumstances.
10.5 Transport & Storage
All goods should be adequately packaged to prevent damage in transit or intermediate
storage.

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11.0 LIMITED WARRANTY
The manufacturer, (Geosense Ltd), warrants the THermistors manufactured by it, under
normal use and service, to be free from defects in material and workmanship under the
following terms and conditions:-
Sufficient site data has been provided to Geosense® by the purchaser as regards the
nature of the installation to allow Geosense® to select the correct type and range of
Thermistors and other component parts.
The Thermistors equipment shall be installed in accordance with the manufacturer’s
recommendations.
The equipment is warranted for 2 years from the date of shipment from the manufacturer
to the purchaser.
The warranty is limited to replacement of part or parts which, are determined to be
defective upon inspection at the factory. Shipment of defective part or parts to the factory
shall be at the expense of the Purchaser. Return shipment of repaired/replaced part or
parts covered by this warranty shall be at the expense of the Manufacturer.
Unauthorised alteration and/or repair by anyone which, causes failure of the unit or
associated components will void this LIMITED WARRANTY in its entirety.
The Purchaser warrants through the purchase of the THermistors equipment that
he is familiar with the equipment and its proper use. In no event shall the
manufacturer be liable for any injury, loss or damage, direct or consequential,
special, incidental, indirect or punitive, arising out of the use of or inability to use
the equipment sold to the Purchaser by the Manufacturer.
The Purchaser assumes all risks and liability whatsoever in connection with the
Thermistor equipment from the time of delivery to Purchaser.

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NOTES

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