AEC SM720 User manual

1
www.alexsensors.com
SM720
Operation Instructions
Capacitive Level Transmitter
Reg. No. 059-A
WARRANTY
2
YEARS

Alex Electronics Co.
SM620 Capacitive Level Switches
SM720

Alex Electronics Co.
SM720 Capacitive Level Transmitter
Contents
1 About this document ..............................................................................................................................2
1.1 Function...............................................................................................................................................................................2
1.2 Target group.........................................................................................................................................................................2
1.3 Symbols used .......................................................................................................................................................................2
1 For your safety........................................................................................................................................3
1.1 Authorized personnel...........................................................................................................................................................3
1.2 Appropriate use ...................................................................................................................................................................3
1.3 Warning about incorrect use ...............................................................................................................................................3
1.4 General safety instructions..................................................................................................................................................3
1.5 Safety label on the instrument .............................................................................................................................................4
1.6 CE conformity......................................................................................................................................................................4
1.7 Environmental instructions..................................................................................................................................................4
2 About the Product ..................................................................................................................................5
2.1 Package Content..................................................................................................................................................................5
3 Installation ..............................................................................................................................................7
4 Connecting to Power Supply ...............................................................................................................10
4.1 Preparing the Connection .................................................................................................................................................10
1.1 Connection procedure .......................................................................................................................................................12
5 Calibration ............................................................................................................................................13
5.1 Calibration Procedures .....................................................................................................................................................13
6 Maintenance and fault rectification....................................................................................................14
6.1 Maintenance ......................................................................................................................................................................14
6.2 Rectify faults ......................................................................................................................................................................14
6.3 Exchanging the electronics module...................................................................................................................................15
7 Disposal .................................................................................................................................................16
7.1 Dismounting steps .............................................................................................................................................................16
7.2 Disposal.............................................................................................................................................................................16
8 Supplement ...........................................................................................................................................17
8.1 Technical Data...................................................................................................................................................................17
8.2 Dimensions ........................................................................................................................................................................18
8.3 Industrial property rights ..................................................................................................................................................19
8.4 Trademark..........................................................................................................................................................................19

Alex Electronics Co.
SM720 Capacitive Level Transmitter
1
Safety instructions for Ex areas
Take note of the Ex specific safety instructions for Ex
applications(Group2 ). These instructions are attached as
documents to each instrument with Ex approval and are part of
the operating instructions manual.

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SM720 Capacitive Level Transmitter 2
1 About this document
1.1 Function
This operating instructions manual provides all the information
you need for mounting, connection and setup as well as important
instructions for maintenance and fault rectification. Please read
this information before putting the instrument into operation and
keep this manual accessible in the immediate vicinity of the device.
1.2 Target group
This operating instructions manual is directed to trained specialist
personnel. The contents of this manual should be made available
to these personnel and put into practice by them.
1.3 Symbols used
Information, tip, note:
This symbol indicates helpful additional information.
Caution:
If this warning is ignored, faults or malfunctions can result.
Warning:
If this warning is ignored, injury to persons and/or serious damage
to the instrument can result.
Danger:
If this warning is ignored, serious injury to persons and/or
destruction of the instrument can result.
Ex applications:
This symbol indicates special instructions for Ex applications.
SIL applications:
This symbol indicates instructions for functional safety which must
be taken into account particularly for safety-relevant applications.
List:
The dot set in front indicates a list with no implied sequence.
Action:
This arrow indicates a single action.
Sequence of actions:
Numbers set in front indicate successive steps in a procedure.
i
SIL
•
1

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SM720 Capacitive Level Transmitter
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1 For your safety
1.1 Authorized personnel
All operations described in this operating instructions manual must
be carried out only by trained specialist personnel authorized by
the plant operator.
During work on and with the device the required personal protective
equipment must always be worn.
1.2 Appropriate use
UTS90 is a sensor for continuous level measurement.
You can find detailed information about the area of application in
chapter “Product description”.
Operational reliability is ensured only if the instrument is properly
used according to the specifications in the operating instructions
manual as well as possible supplementary instructions.
For safety and warranty reasons, any invasive work on the device
beyond that described in the operating instructions manual may
be carried out only by personnel authorized by the manufacturer.
Arbitrary conversions or modifications are explicitly forbidden.
1.3 Warning about incorrect use
Inappropriate or incorrect use of the instrument can give rise to
application-specific hazards, e.g. vessel overfill or damage to
system components through incorrect mounting or adjustment.
1.4 General safety instructions
This is a state-of-the-art instrument complying with all prevailing
regulations and guidelines. The instrument must only be operated
in a technically flawless and reliable condition. The operator is
responsible for the trouble-free operation of the instrument.
During the entire duration of use, the user is obliged to determine
the compliance of the necessary occupational safety measures
with the current valid rules and regulations and also take note of
new regulations.
The safety instructions in this operating instructions manual,
the national installation standards as well as the valid safety
regulations and accident prevention rules must be observed by
the user.
For safety and warranty reasons, any invasive work on the device
beyond that described in the operating instructions manual may
be carried out only by personnel authorized by the manufacturer.
Arbitrary conversions or modifications are explicitly forbidden.
The safety approval markings and safety tips on the device must
also be observed.

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SM720 Capacitive Level Transmitter 4
1.5 Safety label on the instrument
The safety approval markings and safety tips on the device must
be observed.
1.6 Environmental instructions
Protection of the environment is one of our most important duties.
One of our goals is continuously improving company environmental
protection.
Please help us fulfill this obligation by the environmental
instructions in this manual:
• Chapter “Packaging, transport and storage”
• Chapter “Disposal”
1.7 Packaging, transport and storage
Your instrument is protected by packaging during transport.
The packaging of standard instruments consists of environment-
friendly, recyclable cardboard. For special versions, PE foam or PE
foil is also used. Dispose of the packaging material via specialized
recycling companies.
Transport must be carried out in due consideration of the notes on
the transport packaging. Nonobservance of these instructions can
cause damage to the device.
The delivery must be checked for completeness and possible
transit ceiled defects must be appropriately dealt with.
Up to the time of installation, the packages must be left closed
and stored according to the orientation and storage markings on
the outside.
Unless otherwise indicated, the packages must be stored only
under the following conditions:
• Not in the open
• Dry and dust free
• Protected against solar radiation
• Avoiding mechanical shock and vibration
1.8 Accessories and replacement parts
The protective cover protects the sensor housing against soiling
and intense heat from solar radiation.
Electronics module “UTS80” is a replacement part for ultrasonic
sensors of UTS80. A different version is available for each model.
Packaging
Transport
Transport Inspection

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2 About the Product
2.1 Package Content
• SM720 device
• Warranty certificate
• Documentation of operating instructions
• Operating settings
• Serial number
Label Content
Typical Application
Advantages
Fig.1: SM720 Capacitive Level Transmitter
SM720 is suitable for use with liquids and solids.
It is a very accurate measuring device and the most common
measuring technique available.
The sensor works with conductive and non-conductive liquids
Example (water, oil, gasoline ) And fine and coarse grained solids
• Simple calibration steps
• Accurate measuring system
• Maintenance free device
• Capable of measuring solids and liquids
• Suitable for conductive and non-conductive liquids

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SM720 Capacitive Level Transmitter 6
Theory of Operation
Fig.2: Theory of operation
The principle of operation is based on the change of capacitance
between the probe and the silo or vessel wall.
The probe and the vessel wall form a capacitor CX
When the vessel is empty, the isolation medium between the two
electrodes of the capacitor (probe and vessel wall) is air which

When the material inside the vessel covers the probe, the
insulation medium between the two electrodes (probe and vessel

This change in the capacitance value is monitored by the electronic
card (inside the head house) which converts it to equivalent 4 - 20
mAoutput signal.

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SM720 Capacitive Level Transmitter
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3 Installation
When installing the SM720 sensor please check that the fitting
and the sensor material is suitable for the product and the vessel.
Install the sensor in a place that is easy to reach for connection
and calibration steps.
DON’T try to screw the sensor by holding the head doing this will
damage the sensor from inside and damage its electronics.
Instead screw the sensor by using a hexagonal key.
The sensor is installed vertically from above the vessel.
In case of wide diameter vessels choose a place that is 30-40 m
from the vessel wall to achieve the best accuracy.
General Instructions
Installation Position
Fig.3: Installing Position

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Keep the sensor away from the flow source to avoid getting false
signals from the flow material instead of the product surface
The following figure describes this in open flow channel and inside
vessels.
Fig.4: Installing with inflowing medium
Good Bad
Bad
Good

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When installing the SM720 in narrow pipes make sure that the
pipe is connected to the earth and that there is a venting hole near
its top to vent the air inside the pipe and allow the product to rise
inside it.
Review the following figure for more illustration
Installation in pipe
Fig.5: Installing in a shaft
1
.1 Venting Hole
NOTE
Don’t cover the fitting thread with any insulating material, like
Teflon, in order not to affect the sensor operation. If necessary,
connect the earth terminal in the electronic card to the vessel body
In case of non-conductive vessels connect the sensor to an
outside earth plate
i

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SM720 Capacitive Level Transmitter 10
Fig.6: Electronic Module
4 Connecting to Power Supply
4.1 Preparing the Connection
Always keep in mind the following safety instructions:
• Please disconnect supply from power lines before beginning
the connection steps, for your safety and the safety of the
equipment.
• Choose the suitable cable diameter for the cable gland on your
equipment and tighten the cable gland to protect the sensor
from water and humidity.
• In case of high electromagnetic noise expected at the field
of operation, it is recommended to use a shielded cable and
connect the shield to earth terminal.
Safety Instructions
Electronic Module
Two-Wires connection card
Span
LD1
LD2
Zero
AEC
Alex Electronics Co.
IE7XX
- +
1
2
3
4
5
6
789
10
.1 Power LED
.2 Control LED
.3 20mA fine adjust
.4 Span circle
.5 4mA fine adjust
.6 Zero circle
.7 Supply +ve terminal
.8 Supply –ve terminal
.9 Earth terminal
.10 Magnetic Pen
In case of the two wires system, connect the two power lines to
the card as shown in previous figure taking into consideration the
line polarity.

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SM720 Capacitive Level Transmitter
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To read the output signal in this system, it depends on the loop
current in the two wires that allows the user to put as many reading
devices as needed and take the signal for long distance without
problems
Span
LD1
LD2
Zero
AEC
Alex Electronics Co.
IE7XX
- +
+
4-20mA
Span
LD1
LD2
Zero
AEC
Alex Electronics Co.
IE7XX
- +
4-20
24
4-20mA
+
IN
SM720 Sensor Control Panel
1
2
3
4
Fig.7: 2 wires connected to PLC AD card
.1 Supply
.2 DCS control room
.3 Control
.4 PLC Analog card
NOTE
 If the two lines from the supply point are long distance, cables
must be shielded to avoid noise influence on the Signal
2. Connect the cable screen to the earth terminal of the electronic
card
3. Pin 3 in the output terminal is connected to earth, use it when
needed to connect external earth line to your system.
4. The calibration socket is for technical users only and not used
by end users unless you have the calibration module.
i

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5 Calibration
5.1 Calibration Procedures
 Install the sensor proberly following the installation instructions.
2. Fill the vessel to the zero level needed
3. Press zero and hold by touching the zero circle with the
magnetic pen until the LED2 indicator starts to flash then release
immediately.
4. The control card will read the capacitance and Transmits 4 mA
through the wires
Calibration Procedures
Fig.8: Calibration Step 2
Fig.9: Calibration Step 5
5. Start filling the vessel until it reaches the desired span distance.
6. Fill the vessel to maximum level and Press and hold the span
by touching the span circle using the magnetic pen until the
LED2 starts to flash then release immediately.
7. The control card will read the capacitance and transmits 20
mA through the wires

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SM720 Capacitive Level Transmitter
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Reaction when malfunction
occurs
Causes of Malfunction
6 Maintenance and fault rectification
6.1 Maintenance
If the instrument is used properly, no special maintenance is
required in normal operation.
6.2 Rectify faults
The operator of the system is responsible for taking suitable
measures to rectifying faults.
SM720 offers maximum reliability. Nevertheless, faults can occur
during operation. These may be caused by the one following:
• Sensor
• Process
• Voltage supply
• Signal processing
The first measures to be taken are to check the output signals.
The procedure is described below the causes can be determined
and the faults rectified this way.
Connect a multimeter in the suitable measuring range according
to the wiring plan.
The following table describes possible errors in the current signal
and helps to eliminate them:
Error Cause Rectification
• The instrument
signals are
covered without
medium coverage
• The instrument
signals are
covered
with medium
coverage.
Wrong mode
selected on the
signal conditioning
instrument
Change the mode by
mode transmitter
Operating voltage too
low
Check operating
voltage
Short circuit in the
probe, e.g. because
of moisture in the
housing
Remove the
electronics module.
Check the resistance
between the marked
plug connections.
See the following
instructions.
Electronics Defective
Exchange the
instrument or send
it in
Unfavorable
installation location
Check if the probe is
covered by buildup
on the socket. Mount
the instrument at
a location in the
vessel where e.g. no
mounds can form.

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SM720 Capacitive Level Transmitter 14
Remove the electronics module. Check the resistance between
the two plug connections. There must not be a connection
anymore (high impedance). If there is still a connection, exchange
the instrument or return it for repair
6.3 Exchanging the electronics module
If the electronics module is defective, it can be replaced by the
user.
In Ex applications(Group 2) , only instruments and electronics
modules with appropriate Ex approval may be used.
The sensor serial number is necessary. The serial numbers are
stated on the type label of the instrument, inside the housing or on
the delivery note.
To change the electronics modules do the following:
Check the resistance in the
probe
 Turn off the transmitter power supply
2. Unscrew the housing cover
3. Unscrew the terminals of the old module with a screwdriver
4. Pull the connection cables out of the terminals
5. Loosen the screws of the module and the earth with a
screwdriver.
6. Pull out the old electronics module.
7. Compare the new electronics module with the old one. The
type label of the electronics module must correspond to that
of the old electronics module.
8. Insert the electronics module carefully. Make sure that the
plug is in the correct position.
Information:
Make sure that the housing is not rotated during the electronics
exchange. Otherwise the plug may be in a different position later.
9. Screw in and tighten the screws of the module and the earth
terminal with a screwdriver
Insert the wire ends into the open terminals.
Check the hold of the wires in the terminals by gently pulling
on them
Mount the probe into the vessel. Make sure that the probe is
uncovered.
i

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SM720 Capacitive Level Transmitter
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7 Disposal
7.1 Dismounting steps
Warning:
Before dismounting, be ware of dangerous process conditions
such as pressure in the vessel or pipeline, high temperatures,
corrosive or toxic products etc.
Take note of chapters “Mounting” and “Connecting to power
supply” and carry out the listed steps in reverse order.
7.2 Disposal
The instrument consists of materials which can be recycled by
specialized recycling companies. We use recyclable materials
and have designed the parts to be easily separable.
Pass the instrument directly on to a specialized recycling company
and do not use the municipal collecting points.
Correct disposal avoids negative effects on humans and the
environment and ensures recycling of useful raw materials.
Materials: see chapter “Technical data”
If you have no way to dispose of the old instrument properly,
please contact us concerning return and disposal.

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SM720 Capacitive Level Transmitter 16
8 Supplement
8.1 Technical Data
General Data
System Level detection
Process Condition Pressure: up to 20BAR
Temperature: 85ooC
Housing Materia Aluminum
Probe material Isolated Steel wire
Stainless Steel 304
Installation



Protection
Intrinsic safety

IP67
Length Up to 20m
Supply 24Vdc
Output Data 4-20mA
Power consumption Less than 0.5W
Protection applied Reverse polarity protection
Electrical Data

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8.2 Dimensions
SM720 WITH STANDAR PROBE SM720 WITH HIGH TEMP PROBE
100mm
80mm
15mm
30mm
5mm
Wire Length
Probe Length