METER TEROS 11 Manuale utente
TEROS 11/12
i
TABLE OF CONTENTS
1. Introduction..............................................................................................1
2. Operation ...................................................................................................2
2.1 Installation ................................................................................................2
2.2 Connecting................................................................................................. 6
2.2.1 Connect to METER Logger.................................................................6
2.2.2 Connect to Non-METER Logger.........................................................7
2.3 Communication .........................................................................................8
3. System....................................................................................................... 10
3.1 Specifications.......................................................................................... 10
3.2 Components ............................................................................................ 13
3.3 Theory...................................................................................................... 15
3.3.1 Volumetric Water Content .............................................................. 15
3.3.2 Temperature ................................................................................... 15
3.3.3 Electrical Conductivity (TEROS 12 Only) ......................................... 15
3.3.4 Converting Bulk EC to Pore EC (TEROS 12 Only).............................. 15
3.3.5 Pore Water Versus Saturation Extract EC (TEROS 12 Only) ............. 16
4. Service....................................................................................................... 18
4.1 Calibrations ............................................................................................. 18
4.1.1 Mineral Soils................................................................................... 18
4.1.2 Soilless Media ................................................................................ 18
4.1.3 Apparent Dielectric Permittivity..................................................... 19
18225-02
2.15.2019
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4.2 Cleaning................................................................................................... 19
4.3 Troubleshooting....................................................................................... 19
4.4 Customer Support.................................................................................... 20
4.5 Terms and Conditions .............................................................................. 21
References .................................................................................................... 22
Index ................................................................................................................. 23
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1
TEROS 11/12
1. INTRODUCTION
Thank you for choosing the TEROS11 Soil Moisture and Temperature sensor and the
TEROS12 Soil Moisture, Temperature, and Electrical Conductivity (EC) sensor from
METERGroup.
The TEROS11/12 sensors are designed to be installed in mineral soils, many types of
growingmedia, and other porous materials. This manual guides the customer through
thesensor features and describes how to use the sensor successfully.
TEROS 11/12 sensors are accurate tools for monitoring volumetric water content (VWC),
temperature in soil and soilless substrates, and EC (TEROS 12 only). The TEROS11/12
determines VWC using capacitance/frequency-domain technology. The sensor uses a
70-MHz frequency, which minimizes textural and salinity effects, making the
TEROS11/12 accurate in most mineral soils. The TEROS 11/12 uses a thermistor in the
center needle to measure temperature and EC (TEROS 12 only) using a stainless-steel
electrode array.
Prior to use, verify the TEROS11/12 sensor arrived in good condition. METER
recommends testing the sensors with the data logging device and software before going
to the field.
2
OPERATION
2. OPERATION
Please read all instructions before operating the TEROS11/12 to ensure it performs to its full
potential.
SAFETY PRECAUTIONS
METER sensors are built to the highest standards. Misuse, improper protection, or improper
installation may damage the sensor and possibly void the manufacturer’s warranty. Before
integrating the TEROS11/12 into a system, follow the recommended installation instructions
and have the proper protections in place to safeguard sensors from damage. If installing
sensors in a lightning-prone area with a grounded data logger, see the application note
Lightning surge and grounding practices.
2.1 INSTALLATION
Follow the steps listed in Table1 to set up the TEROS11/12 and start collecting data. For more
detailed installation information, consult the TEROS Sensors Best Practices Installation Guide.
Installation
Tools Needed
Auger or Shovel
Secure Mounting Location for Data Logger and Cable
Borehole Installation Tool (Optional)
jack
cradle
carriage
shaft
actuator
lever
flashlight
TEROS
sensor
Preparation
Determine Best Installation Method
There are several methods for installing soil moisture sensors. These methods
are described in Table2.
Conduct System Check
Plug the sensor into the data logger (Section2.2) to make sure the sensor is
operating as expected.
Verify all sensors read within expected ranges. To validate both sensor function
and logger functionality, take a sensor measurement in air and water. The
TEROS11/12 will read ~0.70 m3/m3 in water and a slightly negative value in air.
3
TEROS 11/12
Table 1 Installation (continued)
Installation
There are several methods for installing soil moisture sensors (Table2). Keys to a
good installation and collecting good soil moisture data are described below.
Create Hole
Avoid interferring objects.
• Installations near large metal objects can affect the sensor function and
distort readings.
• Large objects like roots or rocks could potentially bend the needles.
Auger or trench a hole to the desired sensor installation depth and direction
according to the installation method desired.
Insert Sensor
Determine sensor orientation. The TEROS 11/12 sensor may be positioned in
any direction. However, with the body in a vertical position (as shown below),
there is less restriction to water ow. A vertical position will also integrate
more soil depth into the soil moisture measurement. Installing the sensor with
the body in a horizontal position will provide measurements at a more discreet
depth. See Measurement volume of METER volumetric water content sensors
for more information on sensor measurement volume.
Sensor body vertical and needles horizontal
Any metal located between the sensor and the ferrite core can interfere with
VWC measurements and should be avoided.
ATTENTION! Minimize air gaps around the sensor. Air gaps around the sensor needles will
result in low readings of soil moisture.
1. Load the TEROS11/12 using the Borehole Installation Tool (BIT).
NOTE: The BIT provides a significant amount of mechanical advantage.See
2. Lower the tool into the hole or trench with the back of the tool supported
by the far wall.
3. Pull the tool lever to activate the jack and insert the sensor into the sidewall.
WARNING: When installing sensors in rocky soils,use care to avoide bending sensor needles.
4
OPERATION
Table 1 Installation (continued)
Installation
(continued)
Return soil to the hole, packing the soil back to its native bulk density.
Do not hit the ferrite core as this could potentially pull the sensor out of the soil.
Connecting
Connect to Data Logger
Plug the sensor into a data logger.
Use the data logger to make sure the sensor is reading properly.
Verify that these readings are within expected ranges.
For more specific instructions on connecting to data loggers, refer to
Section2.2.
Secure and Protect Cables
NOTE: Improperly protected cables can lead to severed cables or disconnected sensors.
Cabling issues can be caused by many factors such as rodent damage, driving over sensor
cables, tripping over cables, not leaving enough cable slack during installation, or poor
sensor wiring connections.
Install cables in conduit or plastic cladding when near the ground to avoid
rodent damage.
Gather and secure cables between the TEROS 11/12 and the data logger to the
mounting mast in one or more places.
Port1Port2Port3Port4 Port 5Port 6
TEST
OK
ERROR
(-)
(-)(-) (-)
(-)(+)(-)(+)(+)
(+)(+)(+)
Securing excess cable
Table2 contains brief descriptions for typical installation methods. Each has its own
advantages and disadvantages. For more information about which installation method is
best for specific applications, please see the TEROS11/12 Installation Guide or contact
Customer Support.
5
TEROS 11/12
Installation methods
Borehole
This method uses the Borehole
Installation Tool (Table1) that
allows a prole of soil moisture
sensors to be installed at
different depths within a single
augered borehole. A 10-cm (4-in)
borehole is augered vertically at
the measurement location. The
Borehole Installation Tool is then
used to install the sensors in the
sidewall of the borehole.
NOTE: The borehole method
Advantage
Minimizes soil
disturbance at
measurement
site.
Disadvantage
Requires a
specialized
installation
tool that can
be rented from
METER.
Trench
The trench installation method
is best for shallow installations
(less than 40 cm). This requires
digging a trench with a shovel,
excavator, or other tool. The
trench needs to be dug to the
depth of the deepest installed
sensor. For deep installations,
this may require a large trench.
The sensor is installed carefully
by hand into the undisturbed soil
of the trench sidewall. The trench
is carefully backlled to preserve
the bulk density of the soil.
Advantage
Does not
require
specialized
equipment.
Disadvantage
Large soil
disturbance at
measurement
site.
Potentially
large
excavation
effort.
NOTE: Carefully backfill to avoid dislodging the installed sensor by accidentally snagging the ferrite core.
6
OPERATION
2.2 CONNECTING
The TEROS11/12 works seamlessly with METER data loggers. The TEROS11/12 can
also be used with other data loggers, such as those from Campbell Scientific, Inc. For
extensive directions on how to integrate the sensors into third-party loggers, refer to the
TEROS11/12 Integrator Guide.
TEROS11/12 sensors require an excitation voltage in the range of 4 to 15VDC and operate
at a 4VDC level for data communication. TEROS11/12 can be integrated using DDI serial or
SDI-12 protocol. See the TEROS11/12 Integrator Guide for details on interfacing with data
acquisition systems.
TEROS11/12 sensors come with a 3.5-mm stereo plug connector (Figure 1) to facilitate easy
connection with METER data loggers. TEROS 11/12 sensors may be ordered with stripped
and tinned wires to facilitate connecting to some third-party loggers (Section2.2.2).
Ground
Data output
Power
Figure 1 Stereo plug connector
The TEROS11/12 sensor comes standard with a 5-m cable. It may be purchased with custom
cable lengths for an additional fee (on a per-meter basis). METER has successfully tested
digital communication on cable lengths up to 1,000 m (3,200 ft). This option eliminates the
need for splicing the cable (a possible failure point). However, the maximum recommended
length is75 m.
2.2.1 CONNECT TO METER LOGGER
The TEROS11/12 sensor works most efficiently with METER ZENTRA, EM60, and
Em50 series data loggers. Check the METER download webpage for the most recent data
logger firmware. Logger configuration may be done using either ZENTRA Utility (desktop and
mobile application) or ZENTRA Cloud (web-based application for cell-enabled ZENTRA data
loggers).
1. Plug the stereo plug connector into one of the sensor ports on the logger.
2. Use the appropriate software application to congure the chosen logger port for the
TEROS11 or TEROS12.
METER data loggers wil automatically recognize TEROS 11/12 sensors.
3. Set the measurement interval.
METER data loggers measure the TEROS11/12 once every minute and return the average
of the 1-min data across the chosen measurement interval.
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