User Manual for the
EQ3 Equitensiometer
Soil Matric Potential Sensor
EQ3-UM-1.1
Delta-T Devices Ltd
Notices
Patents
The EQ3 Equitensiometer has been jointly developed by Dr. Liu,
Ecomatik and Delta-T Devices Ltd. and uses novel technologies.
They are subject to the following patents:
UK:
US:
GB2300485B
US5804976 & US5898310
Copyright
All parts of the EQ3 design and documentation are covered under copyright law. All rights reserved. Under the copyright laws this book may not be copied, in whole or in part, without the written consent of Delta-T Devices Ltd. Under the law, copying includes translation into another language.
© 2014 Delta-T Devices Ltd
EMC Compliance
See page 28.
Design Changes
Delta-T Devices Ltd reserves the right to change the designs and specifications of its products at any time without prior notice.
User Manual Version:
EQ3-UM-1.1 October 2014
Delta-T Devices Ltd
130 Low Road,
Burwell
Cambridge CB25 0EJ
UK
Tel : +44 1638 742922
Fax : +44 1638 743155 email : [email protected]
web : www.delta-t.co.uk
Contents
Introduction
Description
Features
Behaviour near saturation
Dimensions
Parts list
Care and safety
How the EQ3 works
Operation
Cable Connections
Installation
Delta-T Logger connections and configuration
GP2
GP1
DL6
DL2e
Other data loggers
Logging period and sensor warmup time
Operational considerations
HH2 Meter
Calibration
Sensor calibration
Troubleshooting
Technical Reference
Specifications
Matric Potential
Temperature
EQ3 User Manual 1.1
26
26
26
26
Introduction 3
19
19
20
21
22
22
16
17
18
11
11
12
14
14
24
5
5
6
6
7
8
9
10
Definitions
Soil Matric Potential
Soil Water Content versus Soil matric potential
References
Technical Support
Appendix 1:
The EQ3 Temperature Sensor
Resistance to Temperature Lookup Table
Index
31
33
33
35
36
29
29
29
30
EQ3 User Manual 1.1 Introduction 4
Introduction
Description
The EQ3 Equitensiometer (EQ3) measures soil matric potential and temperature. Soil matric potential is the negative pressure (or suction) required to extract water from between the matrix of soil particles. It is an important indication of plant water stress. The value of soil matric potential measured depends mainly on the quantity of water present and the make-up of the soil, though it is also affected by temperature and salinity.
The EQ3 consists of a precision soil moisture sensor (the
ML3 ThetaProbe) whose measuring rods are embedded in a porous material (the equilibrium body). This material has a known, stable relationship between water content and matric potential. When the probe is inserted into the soil, the matric potential within the equilibrium body equilibrates to that of the surrounding soils. The water content of the matric material is measured directly by the ML3 ThetaProbe, and this can be converted into the matric potential of the surrounding soil using the calibration curve supplied with each
Equitensiometer.
EQ3 User Manual 1.1 Introduction 5
Features
Soil matric potential accurate to:
± 10 kPa from 0 to -100kPa
±10% of reading from -100kPa to -
1000kPa
Hysteresis may add ±20kPa at 0kPa
(see Behaviour near saturation below)
Soil temperature to ± 0.5°C over 0-40°C
Excellent stability
Minimal soil disturbance
Easy installation at depth in augered holes
Waterproof connector to IP68
Rugged, weatherproof and can be buried
Good electrical immunity
Choice of cabling system options
Cable connector, cylindrical profile and extension tube design simplifies removal for servicing.
See also Specifications on page 26
Behaviour near saturation
EQ3 sensors are best used in non-saturated direr soils, best for measurements from -100 to -500 kPa. Our own experience over the years is that the zero readings (saturated conditions) are not well defined, and the curve changes rapidly, meaning that for a very small kPa ‘shift’ in the soil, you get a very large ‘mV’ shift from the sensor.
Our own view, derived from user’s experience over a number of years, is that offset errors at saturation, due to drift or hysteresis in the zero potential mV value are commonly of the of the order of +20mV or more. The EQ3 in other respects seems to continue to behave in a normal fashion, so we don’t think it is a malfunction, rather it is a feature of the sensor.
EQ3 User Manual 1.1 Introduction 6
Dimensions
EQ3 User Manual 1.1 Introduction 7
Parts list
Your shipment may include the following:
Part Sales Code
EQ3
Description
EQ3 sensor
ML/EX50
ML/EX100
50 and 100cm Extension
Tube
SMSC/sw-
05
5m cable with
100 mm flying leads for GP2, GP1 or DL6 logger
SMSC/lw-05
5m cable with 200mm flying leads for DL2e logger
EXT/5W-05
EXT/5W-10
EXT/5W-25
5, 10 and 25m extension cables. IP68 M12 connectors
SMSC/d-
HH2
0.9m cable connects to
HH2 Meter via 25-way
D-connector
SM-AUG-
100
45mm spiral auger
1.2m long
EQ3 User Manual 1.1 Introduction 8
Care and safety
Take care when attaching cables to ensure that the connectors are clean, undamaged and properly aligned before pushing the parts together.
Do not pull the EQ3 out of the soil by its cable.
Keep the EQ3 in its protective tube when not in use.
EQ3 User Manual 1.1 Introduction 9
How the EQ3 works
When power is applied to the EQ3...
...it creates a 100MHz waveform (similar to FM radio).
The waveform is applied to an array of stainless steel rods which transmit an electromagnetic field into a porous material (the equilibrium body).
The water content of the porous material (the equilibrium body) surrounding the rods...
...dominates its permittivity .
(A measure of a material’s response to polarisation in an electromagnetic field. Water has a permittivity
81 and air
1)
V out
The permittivity of the porous material has a strong influence on the applied field…
…which is detected by the EQ3, resulting in a stable voltage output that…
Soil Matric
Potential
-220kPa
...acts as a simple, sensitive measure of soil matric potential.
EQ3 User Manual 1.1 Introduction 10
Operation
Cable Connections
brown white blue black grey green
Power 0V
Power V+
Soil Moisture Signal HI
Soil Moisture Signal LO
Temperature +
Cable shield
HH2 cable
Extension cables
Logger cables
0.9m
5m
10m
25m
5m with
100 or 200 mm bare leads
Take care when attaching cables to ensure that the connectors are clean, undamaged and properly aligned before pushing the parts together.
Screw together firmly to ensure the connection is water-tight.
Extension cables can be joined up to a recommended maximum of
100m
– see Specifications on page 26
EQ3 User Manual 1.1 Operation 11
Installation
Sensor preparation and siting
The EQ3 should be thoroughly wetted before use, and installed at a horizontal or slanting angle. Vertical installation may slow the response time, and also lead to incorrect readings because rainfall running down the side of the probe housing may wet the soil around the probe excessively. This is particularly important if the probe is being installed below the soil surface using a probe extension tube.
Any gaps between the EQ3 and soil should be filled with a quartz powder slurry. Small changes to the soil structure surrounding the probe will not affect readings but it may take a couple of wetting and drying cycles of the soil around the EQ3 before the signal stabilises.
Protect the EQ3 from strong temperature fluctuations and in particular to avoid exposing the electronics and equilibrium body to different temperatures. So avoid installing it with the case exposed to strong sunlight.
Protect the cable before burying it in locations where it may be attacked by soil insects etc.
Soil sampling points
The soil matric potential within a region of soil will be affected by local variations in soil density and composition, rates of percolation, runoff, evaporation and the uptake of water by nearby roots. The resultant differences in pressure will equilibrate over time at a rate which is determined by the local hydraulic conductivity.
It is important to take the degree of variability of these various parameters into account when deciding on the number of probes to use at any particular location. In particular, if the soil is known to be very heterogeneous, or the distribution of roots is very non-uniform, it will be necessary to take measurements from at least three closelyspaced locations.
EQ3 User Manual 1.1 Operation 12
Push the EQ3 into the soil until fully inserted.
Ensure good soil contact.
Note: The EQ3 is not suitable for soil surface temperature measurements. For soil temperature near the surface dig a trench and install horizontally as shown below.
Cover both EQ3 and the first 30cm of cable with at least 5cm of soil.
Installing at depth
Make a 45mm diameter hole, preferably at
>10° to the vertical using the
SM-AUG-100 auger.
Connect an extension tube e.g. ML/EX50
Push the EQ3 into the soil until fully inserted.
Ensure good soil contact, using a quartz powder suspension to help avoid gaps between the sensor and the surrounding soil
(Delta-T sales item QP1)
Alternatively
Dig a trench, and install horizontally.
Frost
The Equitensiometer will withstand frosts, but any readings taken when the water inside the probe is frozen will be meaningless. The
EQ3 temperature sensor can help identify these events.
See also
“The EQ3 Temperature Sensor” on page 33
EQ3 User Manual 1.1 Operation 13
Delta-T Logger connections and configuration
GP2
6 EQ3s can connect to each GP2 wired as a differential, powered sensors.
12 EQ3s can be connected if you do not use the temperature sensor. For this you will also need a 5 gland expansion lid GP2-G5-LID.
These details illustrate connection to Channels 1 and 2:
EQ3 wiring Colour GP2 terminal
Power 0V and Thermistor LO brown CH1 (PGND)
CH1 (PWR) Power V+
Soil Matric Signal HI
Soil Matric Signal LO
Thermistor HI white blue black grey
CH1 (+)
CH1 (-)
CH2(+) and CH2(-)
Cable shield green CH1 (PGND)
With DeltaLINK configured to talk to a GP2, in the Program,
Overview panel define an EQ2x sensor type measurement for the
EQ3 matric potential signal.
In the Properties, Calculation panel enter the unique look-up table supplied with your EQ3 (to convert mV to kPa).
See also Fig 1 on page 15 and page 22.
Define an ML3 (temperature) measurement channel for the EQ3’s soil
temperature sensor. See also page33.
For further configuration details and help see the DeltaLINK 3 1 software online Help for GP2 loggers, the EQ2 Equitensiometer Info
Panel, Help and the GP2 User Manual.
1
The GP2 logger needs the PC logger software DeltaLINK 3. This can be obtained from www.delta-t.co.uk
or the Software and Manuals DVD.
EQ3 User Manual 1.1 Operation 14
1. Click to add new sensor and select EQ2x
2 Enter EQ3 table
Figure 1 Illustration showing the creation, in DeltaLINK, of a GP2 logger channel for the EQ3 by selecting an EQ2x sensor type measurement and inputting the unique look-up table provided with each equitensiometer.
Note also the EQ3 temperature measurement channel created by defining it as a soil temperature measurement with an ML3(temperature) sensor type.
EQ3 User Manual 1.1 Operation 15
GP1
Two EQ3s can connect to each GP1.
Each EQ3 is wired as a differential, powered sensor.
These details illustrate connection to
Channels 1 and 3:
EQ3 wiring
Power 0V and
Thermistor LO
Power V+
Colour GP1 terminal brown white
CH1 (GND) or Temp (GND)
CH1 (PWR)
Matric Potential
Signal HI
Matric Potential
Signal LO
Temperature +
Cable shield blue black grey
CH1 (+)
CH1 (-)
Temp3 (IN) green CH1 (GND)
Use the linearization data provided with the EQ3 to create a linearization file for DeltaLINK formatted as a .TBL file as described in
“Using Linearization table files with DeltaLINK” available in the
DeltaLINK Documents Library folder installed on your PC, or on the
Software and Manuals DVD.
Save the .TBL file to the DeltaLINK Installation folder
Using the DeltaLINK 2 logger software, configure channel 1 or 2 as a custom voltage sensor and in the sensor ’s Input Channel
Properties, Linearization table field select your table from the drop down menu.
Configure channel 3 or 4 as an ML3 (t emperature) sensor.
See also GP1 Quick Start Guide and the DeltaLINK on-line Help.
2 The GP1 needs
the PC logger software DeltaLINK version 3 or later. A free upgrade can be obtained from www.delta-t.co.uk
or from the Software and Manuals DVD.
EQ3 User Manual 1.1 Operation 16
DL6
6 EQ3s can be connected to a DL6.
Each EQ3 is wired as a differential, powered sensor.
A DL6 logger can only read one EQ3 temperature sensor.
These details illustrate connection to channels 6 and 7:
EQ3 wiring
Power 0V
Colour DL6 terminal brown 0V
V+ Power V+
Soil Moisture
Signal HI
Soil Moisture
Signal LO white blue black
Temperature + grey
Cable shield green
IN+
IN-
RES IN+
Use the linearization data provided with each EQ3 to create a unique linearization file for DeltaLINK formatted as a .TBL file as described in
“Using Linearization table files with DeltaLINK” available in the
DeltaLINK Documents Library folder installed on your PC, or on the
Software and Manuals DVD.
Save each .TBL file to the DeltaLINK Installation folder.
Using the DeltaLINK 3 logger software, configure channel 1 to 6 as a custom voltage sensors and in each sensor’s Input Channel
Properties, Linearization table field select your corresponding table from the menu.
Configure channel 7 as a type ML3 (temperature) sensor.
See also the DL6 Quick Start Guide and the DeltaLINK online Help.
3 The DL6 needs
the PC logger software DeltaLINK version 3 or later. A free upgrade can be obtained from www.delta-t.co.uk
or from the Software and Manuals DVD.
EQ3 User Manual 1.1 Operation 17
DL2e
Up to 60 EQ3s can be connected to a DL2e logger (if not using the temperature sensor channel).
Up to 30 EQ3s can be connected if also reading the temperature sensor.
Each EQ3 is connected as a differential, powered sensor.
These details illustrate connection to Channels 57 and 58 using a
LAC1 input card configured in 15-channel mode, and warm-up channel
63:
EQ3 wiring
Power 0V
Colour DL2e terminal brown CH62- or 61-
CH63 NO Power V+
Soil Moisture
Signal HI white blue
Soil Moisture
Signal LO black
Temperature + grey
Cable shield green
CH58+
CH58-
CH57+ and CH57-
CH61- or 62-
Two sensor configuration codes are supplied with the DL2e: E2D is intended for linearizing the full range of EQ3 output (0 to -1000kPa), and E2W which provides more resolution at the wet end only (0 to -
350kPa). You will need to enter the individual linearization table values attached to the calibration data that is supplied with each of your
EQ3s. See the DL2e User Manual and the Ls2Win online help.
EQ3 User Manual 1.1 Operation 18
Other data loggers
The EQ3 should be connected as a differential, powered sensor.
Configure the logger to convert the EQ3 readings from millivolts into soil matric potential units by using the unique linearization tables or polynomial supplied on the data sheets with each sensor.
See the example on page 22.
Output signals in the range 0 to 1.0 volts from the EQ3 correspond to a range of soil matric potential of 0 to -1000kPa
The temperature sensor output should be read as a resistance and the logger configured with a look-up table to covert the measured resistance to temperature.
See EQ3 Temperature Measurement on page 33
and Resistance to Temperature Lookup Table on page 35.
Note: each Equitensiometer needs its own linearisation table.
Logging period and sensor warmup time
For guidance on a suitable logging frequency it may be helpful to
inspect the EQ3 response time table on page 20
If unsure try logging once every 20 minutes.
The logging frequency should be no faster than once per minute.
Use a one second warmup time.
It is recommended that the sensor is not powered continuously (in order to prevent thermistor self-heating affecting signal accuracy).
EQ3 User Manual 1.1 Operation 19
Operational considerations
Hysteresis and response time effects
The EQ3 only reads correctly once the equilibrium state within the probe is reached with the surrounding soil. Normally there is a time lag between the change of matric potential of the surrounding soil and the response of the EQ3 due to the quality of the hydraulic connection between the EQ3 and soil. This time lag is greatest when the soil matric potential is changing fast, and at large (negative) matric potentials, see Table 1.
Under natural conditions, changes in matric potential are normally less than 0.01 kPa/min, so the associated errors will therefore be much lower than the values in Table 1.
Table 1: Response time of the EQ3 in a rapid drying test. The values are much higher than under natural conditions.
Matric potential, absolute changes
kPa kPa/min
-98
Errors in kPa after minutes
0 10 30 60 120 180 300 360
-.11 2.2 0.3 0 0 0 0 0 0
-215
-376
-.15 5.6 5.3 2.6 0 0 0 0 0
-.37 20.2 19.1 18.0 16.2 13.5 10.1 3.4 0
Soil properties and salinity
The EQ3 is unaffected (or damaged) by physical soil properties
(organic matter, stones, bulk density) and most chemical soil properties (e.g. pH). No tests have been carried out in saline soils, so the performance of the EQ3 in saline soils is unknown.
EQ3 User Manual 1.1 Operation 20
HH2 Meter
You need version 2.7 or later of the PC software
HH2Read and version 2.7.1 of the HH2 firmware.
4
Connect the EQ3 to the HH2 meter.
Press Esc to turn the meter on, and if necessary press again until the HH2 displays the start-up screen.
Set the meter to read from an EQ2 (or EQ2/3 from version 2.7.1):
►
Press Set and scroll down to the Device option.
►
Press Set again and scroll down to select EQ2 or EQ2/3.
►
Press Set to confirm this choice.
Device: EQ2/3
Press Read to take a reading.
Press Store to save or Esc to discard the reading.
EQ2/3 Store?
220mV
If you have saved data, connect your HH2 to a PC and run HH2Read to retrieve the readings.
Note: the HH2 does not display or store EQ3 temperature readings..
The HH2 does not display EQ3 matric potential readings in kPa but only records the output in mV. To convert the reading to kPa requires use of the look up table provided with the EQ3
.
4 Go to www.delta-t.co.uk
for the latest updates
EQ3 User Manual 1.1 Operation 21
Calibration
Sensor calibration
Each EQ3 is individually calibrated to provide consistent dielectric performance and is supplied with the following calibration document.
EQ3 User Manual 1.1 Operation 22
EQ3 User Manual 1.1 Operation 23
Troubleshooting
Always try to identify which part of the measurement system is the source of the difficulty. For the EQ3 this may fall into one of the following areas:
The measurement device
What equipment is being used to read the probe output?
A Delta-T HH2 Moisture Meter.
Note: the HH2 does not measure EQ3 temperature and can only read the matric potential output in mV
A Delta-T data logger such as the GP1, GP2, DL6 or
DL2e
Check versions
Check you have the correct versions:
HH2 Meter: Firmware version 2.7.1 and PC software
HH2Read version 2.7 or later are recommended.
GP1, GP2 & DL6 Loggers: DeltaLINK version 3.0 or later is required.
DL2e Logger: Ls2Win 1.0 SR10 is required
Consult the user manuals or the on-line help for these devices and their related software.
Try alternative types of equipment if you have them available.
The EQ3 itself
Try to isolate the problem into one of the following areas
The EQ3 or the connecting cable
Then try to narrow down the area further
Mechanical problems faults, or damage
Electrical or electronic problems or faults
EQ3 User Manual 1.1 Troubleshooting 24
Maintenance and functional check
Large concentrations of Sodium ions may affect the calibration curves. If the equilibrium body becomes contaminated, the sodium may be washed out by repeatedly wetting it in de-ionised water, and then drying it out by inserting it into a dry non-saline soil.
Washing and then drying in air does not help, because in that
case no exchange of water or solute can take place.
The following simple check can be used to establish whether your EQ3 is functioning within expected bounds:
The calibration should be stable for ~2 years. It can be checked by putting the probe into de-ionised water and checking the reading against the 0 kPa value in its calibration table - at 20°C the reading should be within ± 20 mV. If recalibration is required the probe will need to be returned to
Delta-T Devices.
No other maintenance is required.
EQ3 User Manual 1.1 Troubleshooting 25
Technical Reference
Specifications
Matric Potential
Accuracy
Measurement range
Hysteresis
Soil Types
Output Signal
Output compatible with
10kPa over 0 to -100kPa,
±5% of reading over -100 to -1000kPa
0 to-1000kPa (-10bar)
Not detectable if the change of matric potential is slower than 0.1kPa/min.
Suitable for all non-saline soil types
0-1V differential, non-linear. (Calibration data and graph supplied with each sensor)
GP1, GP2, DL6, DL2e, HH2
Temperature
Sensor accuracy
Output
Output compatible with
Cabling error contribution
(to temperature readings)
Maximum cable length
Power requirement
Operating range
Environment
Dimensions/weight
EQ3 must be fully buried to accurately measure soil temperature
0.5°C over 0-40°C
not including logger or cabling error
Resistance: 5.8kΩ to 28kΩ
GP1, GP2, DL6 5 , DL2e, HH2
Negligible for GP1, GP2 & DL6 (any cable length)
Negligible for DL2e (with 5m cable) 6
100m (GP1, GP2 & DL6 data loggers)
100m (DL2e: water content measurement)
25m (DL2e: temperature measurement)
5-14VDC, 18mA for 0.5 to 1s
-0 to +40°C (Not damaged by use in frozen soils)
IP68
4 Note: The DL6 has only one temperature channel. The DL6 error contribution to EQ3 temperature measurement is negligible compared to the accuracy of the EQ3 temperature sensor itself. The two only become comparable below -15C.
5 DL2e Logger users can apply a correction in the Ls2Win logging software (for cable lengths >5m)
EQ3 User Manual 1.1 Technical Reference 26
Temperature response of soil matric potential readings
The effect of temperature on the EQ3 soil matric potential readings in any particular soil will depend on a combination of effects:
The EQ3 soil moisture electronic circuit has a very low temperature sensitivity, and so this makes a negligible contribution to the overall sensitivity.
The refractive index of water reduces as the temperature increases. This produces a negative temperature response as a result of the water contained in the porous material (the equilibrium body) of the EQ3.
Note: ice has a quite different refractive index from water, so
EQ3 soil matric potential readings cannot be interpreted reliably when inserted into soil below 0°C.
EQ3 User Manual 1.1 Technical Reference 27
Electromagnetic Compatibility (EMC)
General information
EQ3 is a Class A product, intended for operation in non-residential environments.
Only use cables and accessories authorised by Delta-T (sensor cables from other sources for example may adversely affect product performance and affect quality of results).
If possible route cables along the soil surface or bury them – this also reduces possible trip hazard and animal damage.
Do not modify the product or its supplied accessories.
The ML3 EMC Guidance on the Software and Manuals DVD Issue
3 provides additional relevant information.
Regulatory information
Europe
This device conforms to the essential requirements of the EMC directive 2004/108/EC, based on the following test standards:
EN61326-1:2006 Electrical requirement for measurement, control and laboratory use. EMC requirements: Group 1, Class A equipment – (emissions section only).
EN61326-1:2006 Electrical requirement for measurement, control and laboratory use. EMC requirements: Basic Immunity (immunity section only).
FCC compliance (USA)
This device conforms to Part 18 of FCC rules – Industrial, Scientific
& Medical Equipment.
Note: with reference to FCC Part 18.115 Elimination and investigation of harmful interference.
(a) The operator of the ISM equipment that causes harmful interference to radio services shall promptly take appropriate measures to correct the problem.
EQ3 User Manual 1.1 Technical Reference 28
Definitions
Soil Matric Potential
Studies of plant growth need to characterise the availability of water to the plant, and this is usually done using the water potential,
, which measures the suction necessary to extract water from the soil, and has units of pressure, kPa.
Components of this water potential are contributed by gravity, atmospheric pressure, osmosis, and the capillary action of the soil particles. This last component, called the Soil Matric
Potential,
M
, is highly dependent on the wetness of the soil, and varies from 0 kPa at field capacity, down to approximately -1500 kPa at the permanent wilting point.
Soil Water Content versus Soil matric potential
The relationship between soil matric potential and soil water content is called the soil water release curve (it seems to have about 5 other names as well). It differs enormously from one soil to another, particularly from clay soils at one extreme to sandy soils at the other. There is no generalised method of converting from soil water content to matric potential, though a number of expressions have been found which have been successfully applied to a restricted list of soil types, see for example references 2 and 3.
EQ3 User Manual 1.1 Technical Reference 29
References
1.
2.
.
3.
Gaskin, G.J. and Miller, J.D., 1996
Measurement of soil water content using a simplified impedance measuring technique.
J. Agr. Engng Res 63, 153-160
Campbell, G.S., 1974. A simple method for determining unsaturated conductivity from moisture retention data . Soil
Sci. 117:311-314 van Genuchten M. Th., 1980, A closed-form equation for predicting the hydraulic conductivity of unsaturated soils . Soil
Sci. Soc. Am. J. 44 892-898.
EQ3 User Manual 1.1 References 30
Technical Support
Terms and Conditions of Sale
Our Conditions of Sale (ref: COND: 06/14) set out Delta-T's legal obligations on these matters. The following paragraphs summarise
Delta-T's position but reference should always be made to the exact terms of our Conditions of Sale which will prevail over the following explanation.
Delta-T warrants that the goods will be free from defects arising out of the materials used or poor workmanship for a period of twenty four months from the date of delivery.
Delta-T shall be under no liability in respect of any defect arising from fair wear and tear, and the warranty does not cover damage through misuse or inexpert servicing, or other circumstances beyond their control.
If the buyer experiences problems with the goods they shall notify Delta-T
(or DeltaT’s local distributor) as soon as they become aware of such problem.
Delta-T may rectify the problem by replacing faulty parts free of charge, or by repairing the goods free of charge at Delta-T's premises in the UK during the warranty period.
If Delta-T requires that goods under warranty be returned to them from overseas for repair, Delta-T shall not be liable for the cost of carriage or for customs clearance in respect of such goods. However, Delta-T requires that such returns are discussed with them in advance and may at their discretion waive these charges.
Delta-T shall not be liable to supply products free of charge or repair any goods where the products or goods in question have been discontinued or have become obsolete, although Delta-T will endeavour to remedy the buyer’s problem.
Delta-T shall not be liable to the buyer for any consequential loss, damage or compensation whatsoever (whether caused by the negligence of the
Delta-T, their employees or distributors or otherwise) which arise from the supply of the goods and/or services, or their use or resale by the buyer.
Delta-T shall not be liable to the buyer by reason of any delay or failure to perform their obligations in relation to the goods and/or services if the delay or failure was due to any cause beyond the DeltaT’s reasonable control.
EQ3 User Manual 1.1 Technical Support 31
Service, Repairs and Spares
Users in countries that have a Delta-T distributor or technical representative should contact them in the first instance.
Spare parts for our own instruments can be supplied and can normally be despatched within a few working days of receiving an order.
Spare parts and accessories for products not manufactured by Delta-T may have to be obtained from our supplier, and a certain amount of additional delay is inevitable.
No goods or equipment should be returned to Delta-T without first obtaining the return authorisation from Delta-T or our distributor.
On receipt of the goods at Delta-T you will be given a reference number. Always refer to this reference number in any subsequent correspondence. The goods will be inspected and you will be informed of the likely cost and delay.
We normally expect to complete repairs within one or two weeks of receiving the equipment. However, if the equipment has to be forwarded to our original supplier for specialist repairs or recalibration, additional delays of a few weeks may be expected.
For contact details see below.
Technical Support
Users in countries that have a Delta-T distributor or technical representative should contact them in the first instance.
Technical Support is available on Delta-T products and systems. Your initial enquiry will be acknowledged immediately with a reference number. Make sure to quote the reference number subsequently so that we can easily trace any earlier correspondence.
In your enquiry, always quote instrument serial numbers, software version numbers, and the approximate date and source of purchase where these are relevant.
Contact details:
Technical Support
Delta-T Devices Ltd
130 Low Road
Burwell
Cambridge CB25 0EJ
England (UK)
Tel : +44 1638 742922
Fax : +44 1638 743155
E-mail : [email protected] [email protected]
Web : www.delta-t.co.uk
EQ3 User Manual 1.1 Technical Support 32
Appendix 1:
The EQ3 Temperature Sensor
EQ3 Temperature Measurement
The EQ3 Temperature sensor uses the same thermistor as that used in the ML3 ThetaProbe which has a 10K resistance at 25 ˚C.
However:
A. This sensor has a different response curve from the more widely used 10K3A1B type. The response curve is given in the
Resistance to Temperature Lookup Table on page 35.
B. The Thermistor circuit shares the Power 0V wire. If the thermistor is measured when the EQ3 is powered, the measured resistance measurement may need to be corrected for 18 mA EQ3 supply current.
GP2, GP1 and DL6 Loggers
The ‘ML3 (temperature)’ sensor type in DeltaLINK 3 should be used as this performs the supply current correction.
DL2e Logger
The linearization table for the ‘S3T’ sensor code (‘ML3
Temperature’) provides supply current correction for the
SMSC/lw-05 5m logger cable ONLY.
Extension cables and other cable lengths
Create your own custom sensor type(s) and linearization tables as described in Ls2Win Help topic, How to… ‘Add or modify a sensor type in the sensor library’.
Enter corrected resistance values (R) for each linearization table point:
R = R5 + (0.059 x Lex) kΩ (See footnote 7 ) or R = R5 + (0.9 x Rc – 0.297) kΩ
7 Note: This equation only applies to Delta-T ML3 cables
EQ3 User Manual 1.1 Appendix 1: 33
where
R5
= value supplied in the table for the ‘ML3 Temp, 5m’ sensor type.
Lex = length of extension cable, excluding the 5m of SMSC/lw-05 cable.
Rc = total cable resistance, including resistance of SMSC/lw-05 cable, if fitted.
Other loggers
If your logger can be programmed so that the soil matric potential and temperature readings can be taken sequentially (i.e. the sensor is not powered during the temperature reading), then the temperature can be obtained directly from the response curve on
page 35.
Otherwise, correct the resistance reading before applying the response curve.
You need to know the resistance of the Power 0V wire in the EQ3 cable (Rc) and establish whether your logger uses voltage or current excitation for resistance measurement.
Voltage Excited
You need to know the excitation voltage (Vref), reference resistance (Rref).
The correct resistance is given by the equation:
R = a0 + a1 * Rmeas
Where: a0 =
– Ic.Rc.Rref / Vref a1 = 1
– Ic.Rc / Vref
Ic = 18 mA (EQ3 sensor supply current)
For Delta-T EXT/5W-xx series cables:
Rc = 0.066 Ω.m
-1
For the SMSC/lw-05 5m logger cable
Rc = 0.33 Ω
Current Excited
You need to know the excitation current (Iex).
The corrected resistance is given by the equation (using terms defined above):
R = Rmeas
– Ic.Rc/Iex
EQ3 User Manual 1.1 Appendix 1: 34
Resistance to Temperature Lookup Table
Note: This table has been optimised for use as a look-up table.
To minimise linear interpolation errors the data points fall either side of the manufacturer’s specified sensor response curve. This helps optimise the overall accuracy of readings.
EQ3 User Manual 1.1 Appendix 1: 35
Index
A
Accuracy saturation errors, 7
Auger, 10
C
Cable connections, 12
Cable length correction, 36
Calibration check, 28 sensor, 24
Care and Safety, 10
Certification emc, 31
Connections, 15
Copyright, 2
D
Data logger , 21, 26
DL2e, 26
DL6, 26
GP1 , 19, 26 other data loggers, 21
Definitions, 32
Description, 6
Dielectric performance, 24
Dimensions, 8
DL6, 18
EMC, 31
Extension cables, 12
E
EQ3 User Manual 1.1
FCC compliance, 31
Features, 7
F
G
GP1, 17, 19, 26
GP2, 15
H
HH2, 9, 23, 26
I
Installation buried, 14
M
Matric potential, 11, 29, 32
Meter, 26
ML3, 6, 15, 17, 19, 31, 36, 37
P
Parts, 9
Permittivity, 11
R
References, 33
Regulatory information, 31
Rods, 11
Index 36
Pair of sensor rings
S
Sales code, 9 saturation, 7
Servicing, 35
SMSC/lw-05, 36
Soil matric potential, 32
Soil water content, 32
Soil water release curve, 32
Specifications, 2, 29
T
Technical support, 34, 35
Temperature cable length correction, 21, 36
Temperature response of soil moisture readings, 30
Temperature sensor cable length correction, 37
Temperature Sensor Lookup Table, 39
Troubleshooting, 26 ty, 15
W
Warning
Care and Safety, 10
EQ3 User Manual 1.1 Index 37
