INSTALLATION, OPERATION ANDMAINTENANCE INSTRUCTIONS
Capacitive Level Sensor SC 404
2Phone (516) 935-8001 / Fax (516) 935-6001
3456
7, 89, 10
11121314
Contents
Introduction .............................................................................Features & Dimensions .......................................................... Handling .................................................................................Installation .............................................................................. Wiring diagram ...................................................................Calibration ..........................................................................Maintenance ...........................................................................Technical specifications ..........................................................Trouble shooting .....................................................................Ordering information ..............................................................
Introduction
3
SC 404
The wide range of applications for RF analog level measurement probes (such as liquids, pastes, solids and granules), requires attention in selecting the correct level probe and installing it in the proper location. The probe is the primary measuring element and must be capable of producing enough capacitance variance as it becomes submerged in the measured product. To cater to all applications, Sitron's probes are offered with different designs and features. The success of how the probes are applied depends on these important factors:
A) Materials that are conductive can cause a short circuit between a bare stainless steel probe and the tank wall. As the liquid level drops, the probe remains wetted, providing a conductive path between the probe and the tank wall. The faster the level changes, the more likely this false indication is to occur. For this situation, we recommend the use of Teflon or other types of insulator coatings on the rod's surface.
B) Materials build-up also affects the accuracy of RF capacitive measurements, and therefore additional adjustment to the probe's sensitivity is recommended.
Housings must also be compatible with the requirements for hazardous, wash-down, wet, and/or dusty environments. Explosion-proof environments may require the housing to be certified. In addition, the active probe might need to be intrinsically safe or have an intrinsic safety barrier.
The electronic circuitry of the probe performs several functions such as rectifying and filtering the incoming power, generating the radio frequency signal, measuring the changes in current flow, analog signal generators and display meters. The circuitry is provided with potentiometer adjustments for setting sensitivity that is located in the housing of the probe. These adjustments give an added level of fine-tuning which enable our customers to control the probes sensitivity with greater accuracy.
4
Features and Dimensions
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Wide range of applications/industries I.e. water, oils, corrosives, solids, powders, grains, etc. Functions on conductive as well as non-conductive medias No moving partsRugged construction Accurate and reliable measurement Unaffected by coating media or aggressive products Can operate at high temperatures and pressure
L
3/8”
L
3/8”
3 1/2” ( 88 mm )
2 1
/2”
( 6
4 m
m )
SC 404 SC 404 EX
3 1/2” ( 88 mm )
4 1
/4”
( 11
4 m
m )
5
Handling
Do not turn or handle by the housing
Seal the threadwith teflon tapebefore screwing
Use the correct tool to screw the switch
Installation
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INCORRECT CORRECT
The SC404 level sensor must be installed utilizing the type of connection provided. The tank must be free from turbulence or vortices throughout use. When tightening the sensor, use only use the 316S.S. hexagon fitting to achieve a seal, do not twist with the body of the sensor.
Note: As achieving a proper seal it is very important for high pressure and explosion proof applications that care should be taken when tightening the connection.
When installing the sensor either directly to the tank, or utilizing a connection, the capacitance probe should be mounted on the top of the tank, so that the rod stays parallel to the tank wall. Positioning the probe closer to the tank wall than to the center of the tank and away from the point where the medium enters the tank is preferable (see drawing below). This will reduce the chance of false reading when the tank is being filled. It is important however, that the probe does not touch the tank wall or any structural elements within the tank. In addition, the probe should not be mounted where material can form a bridge between the rod and the tank wall.
Care should also be taken when handling and installing sensors with coated rods. Any scratch can affect the performance of the sensor.
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7
Wiring Diagram
Electrical Connection:
The electrical connection is available in a plug-in three way terminal block that can be removed for wiring connections more easily. Use only shielded cable to wire these connections.
The power supply required is 12...30Vdc
+ Positive power supply - Negative power supply (4-20mA) Ground
Important: Do not ground the negative. There are several types of PLC's configurations and some of them have the negative grounded internally. In this case, a galvanic isolator must be used along with the probe to distinguish both signals (negative and ground).
Remove the enclosure lid (Note: the screws are self-retaining)
Use the cable gland to seal and protect the electronic circuit inside the enclosure.
The housing may be rotated after tightening to leave the cable gland in a suitable position.
++--
U = 12 … 30 VdcU = 12 … 30 Vdc
Wiring Diagram
L1L1
2 3 41
A B C
SpanZero
SC 404
PowerSupply
IN
4...2
0 m
A
4...2
0 m
A
ISO
42
0
Zo
ne
0O
UT
1112
12
++__
++__
mmx
Galvanic Isolator
22 ... 24 DC
__
++PowerSupply
Electrical connection using the Galvanic Isolator
L1L1
2 3 41
A B C
SpanZero
SC 404
4 ... 20 mA
0 ... 100 %
PowerSupply
Connect directly to the power supply
L1L1
2 3 41
A B C
SpanZero
+-
SC 404
12 … 36 Vdc
Sensitivity adjustmentSensitivity adjustment
Zero and SpanAdjustment
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9
Calibration
The dielectric value varies according to the product, temperature, pressure, rod's length and shape of the tank. Because of these variations, the parameters of the capacitive probe need to be adjusted according to each application.
The SC 404 has 4 stages of sensitivity that can be adjusted by a selective switch. Each stage has 3 subdivisions (A, B, C) to be combined with the selective switch. Check the values on the chart below according to your application.
Capacitange range:
1 1600pF to 5500pF A - 3750 to 5500pFB - 2500 to 3750pFC - 1600 to 2500pF
2 400pF to 1500pF A - 900 to 1500pFB - 600 to 900pFC - 400 to 600pF
3 100pF to 330pF A - 225 to 330pFB - 150 to 225pF C - 100 to 150pF
4 25pF to 150pF A - 150 to 100pFB - 100 to 70pFC - 70 to 25pF
L1L1
2 3 41
A B C
SpanZero
++--
SC 404
Selectivity switch
12 … 36 Vdc
Positions A,B,C
Adjust of zero and span
10Phone (516) 935-8001 / Fax (516) 935-6001
Calibration
Minimum Adjustment (4mA):
Maximum Adjustment (20mA):
1) Drain the tank to minimum level (0% - level).2) Select the switch 1,2,3, or 4 and positions A, B or C. It is recommended
to begin with switch 1 and position A. 3) Use the Zero potentiometer to set the current value for the actual level
to 4mA. Turn the potentiometer clockwise to increase current. Turn the potentiometer counter-clockwise to decrease current.
It is recommended that an ampere meter be connected according to the figure below to monitor the current value during the calibration.
1) Fill up the tank to maximum level (100% - level).2) The switch should be in the same position as adjusted to 4mA.3) Use the Span potentiometer set the current value for the actual level to
20mA. Turn the potentiometer clockwise to increase current. Turn the potentiometer counter-clockwise to decrease current.
It is recommended that an ampere meter be connected according to the figure below to monitor the current value during the calibration.
If the current is lower than 20mA, it is necessary to increase the sensitivity by selecting the next level of the switch (#2). If the current still remains lower than 20mA, continue on to the next level until you achieve 20mA.
With the 20mA signal adjusted, keep the switch on the same position and adjust the minimum level to 4mA one more time.
After this stage, set-up is complete.
L1L1
2 3 41
A B C
SpanZero
SC 404
12...30Vdc
++
Positive
Negative
Ampere meter
++
--
--
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Maintenance
When cleaning the rods use a soft brush or any other similar object.
PROBES:
Care should be taken when handling and installing transmitters with coated rodsto avoid scratching them.Scratching the coating could interfere with the probe performance.
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Technical Specifications
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SC 404 SC 404 EX
Application
OperatingVoltage
Current Consumption
Adjustment
Sensitivityrange
Frequencyoscilation
Zero & SpanPotentiometer
Zero & SpanPotentiometer
4...20mA (2 wires) 4...20mA (2 wires)
12...30 Vdc 12...30 Vdc
100 to 5500pF 100 to 5500pF
400K Hz 400K Hz
-- --
Continuous level measurement for liquids solids and granular
Continuous level measurement for liquids solids and granular
Output
Repeatability
Level indication
Max pressure 290 PSI (20 Bar) 290 PSI (20 Bar)
IP 65 Eex II B,C
Accuracy 0,5% 0,5%
+/- 1mm
----
+/- 1mm
Enclosure material
Glass fillednylon
Alluminum Die CastExplosion Proof
Wetted material
316 SS 316 SS
Class Protection
Processconnection
3/4” to 1 1/2” BSP or NPTflange or sanitary connections
3/4” to 1 1/2” BSP or NPTflange or sanitary connections
Operatingtemperature
14 to 248º F(-10 to 120ºC)
14 to 248º F(-10 to 120ºC)
MODELS
Electricalconnection
½”NPT Cable gland or M12 connector
1/2” or 3/4” NPT
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Trouble shooting
Does not signal
The signal is overthan 22mA
Fault
Capacitance short
Noise outputThe signal is notfixed
No powerWrong connection
Cause
Check the ground connection
Check if the probe is coatedfor conductive mediums
Check power supplyCheck the polarity of the power
Solution
Ordering Information
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Code
SC404SC120
Code
1
2
3
4
5
6
78
Code
B
NX
Code
20
40
60X
Code
NYEX
Code
C
M
1/23/4
Code
PTFE
0X Other - Specify
NOTE:
RODS MUST BE COATED WHEN USING THE PROBE WITH CONDUCTIVE MEDIUMS.
CodeCN200
Code
24
1123
Note:
CONTINUOUS LEVEL MEASUREMENT
Glass filled nylonAluminum die cast
3/4"NPT (alum.enclosure only)
Electrical Connection
Cable entry
M12 connector
1/2"NPT (alum.enclosure only)
L=40" (L=1000mm)
L=60" (L=1500mm)Other - Specify
Enclosure
NPTNot a thread
Rod's Length
L=20" (L=500mm)
Flange 4" ANSI, 150lb. 316 S.S.Other - Specify
Type of Thread
BSP
ORDERING INFORMATION
Probe to be used along with CN200 transducer (see specs. below)
3/4" Thread
1" Thread
Coating
Teflon
None
Specifications
Supply Voltage: 12...30VDC Output: 4-20mA (2 wire)
Process Connection
1 1/2" Thread
1 1/2" Tri-Clamp
Flange 2" ANSI, 150lb. 316 S.S.
Flange 3" ANSI, 150lb. 316 S.S.
SpecificationsTransducer to be used along with probe SC120
Supply Voltage
24 VDC + - 10%
The CN200 output is: 2 relay (SPDT) 5A max. 250VAC, 4-20mA (2 wire) and 0-5VDC for all options.
115 VAC230 VAC
Sitron-USA, Inc.PO Box 7000
New York, NY 10128Tel: (516) 935-8001 / Fax:(516) 935-6001
e-mail: [email protected]: www.sitron.com