Dwyer CLS2 Manual

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Series CLS2 Capacitive Level Switch

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Specications - Installation and Operating Instructions

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The CLS2 Capacitive Level Switch was designed to sense material level in a wide range of applications and environments using the dielectric properties of the sensed material. State of the art sensing technology in the CLS2, using impulse RF admittance measurement combined with an active guard, provides excellent level measurement and stability while being insensitive to material buildup. This technology also provides immunity to external RF sources like walkie-talkies and cell phones as well as minimal interference with radio communication or other electronic systems.

The product features automatic calibration and 8 selectable sensitivity levels. Calibration may be initiated with either the internal switch or using the external calibration magnet allowing calibration without removing the cover. A selectable failsafe mode allows the relay to be active either normally open or normally closed. The unit also features an active guard mechanism that effectively eliminates the effects of material buildup on the probe. A selectable delay is provided to ensure false detection due to splashing or other tank disturbances will not cause nuisance triggering. A high brightness LED indicator is provided externally so that the level status can be easily seen even in bright sunlight. Three multicolored LEDs are provided internally for maintenance and diagnostic use.

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SPECIFICATIONS

Service: Liquids, powder, and bulk materials compatible with wetted materials.

Wetted Materials: 316 SS and PVDF. Temperature Limits: Ambient: -40 to 185°F (-40 to 85°C), -4 to 185°F (-20 to 85°C)

with under 24 VAC/DC power supply; Process: -40 to 250°F (-40 to 121°C).

Pressure Limit: 365 psi (25 bar). Enclosure Rating: Watertight/corrosion resistant, NEMA 4X. Switch Type: DPDT (two form C). Electrical Rating: 8A @ 120/240 VAC res., 30 VDC; 1/4 HP @ 120 VAC; 1/2 HP @

240 VAC. UL approved rating: 8A @ 120/240 VAC res., 1/2 HP @ 240 VAC.

Power Requirements: 12-240 VAC/DC. Power Consumption: 2.8 watts max. Electrical Connection: 1/2˝ NPT conduit opening, screw termination with

removable terminal block.

Process Connection: 3/4˝ male NPT. Optional 1-1/4˝ male NPT; 1˝, 1-1/2˝ BSP; 1, 1-1/2˝, 2˝ sanitary.

Mounting Orientation: Vertical or horizontal. Set Point Adjustment: Trips when product touches probe. Cut or extend probe

to length of desired trip point. Can be cut as short as 1˝ and can be extended by

welding on to probe (Minimum length will be effected by material being sensed.).

Response Time: 0.2 s. Time Delay: Adjustable, 0 to 60 s. Spark/Static Protection: 1.0 MEG Ohm dissipation resistance with spark gap.

Surge current to 100A max. Sensitivity: 8 Selectable settings, 1, 2, 4, 6, 8, 10, 14, 20 pF (at 30 pF nominal free capacitance). Environmental Conditions: a) Pollution degree 2; b) Indoor and outdoor use; c) Altitude: 2000 meters max; d) Humidity: 0 to 90% up to 104°F (40°C) non-

condensing, 10 to 50% at 140°F(60°C) non-condensing; e) Overvoltage category II.

Compliance: UL.

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DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Phone: 219-879-8000

Fax: 219-872-9057

www.dwyer-inst.com

e-mail: info@dwyermail.com

MODEL CHART Example CLS W 1 1 R K 1 019 M20 CLS2-W11RK1-019-M20

Series CLS Capacitive level switch

Enclosure W Watertight/corrosion resistant

Switch 1 DPDT rated 8A @ 12/240 VAC, 30 VDC res.

Power Supply 1 12-240 VAC/DC Probe Type R

Insulator Material K PVDF Process Connection

Probe Length XXX Insertion length in inches. Example 019 is 19˝ length.

Options M20

1 2 3 4 5 6 7 8

Standard rod: 316 SS, .375˝ diameter

Cable: 316 SS with weight

3/4˝ male NPT 1˝ male NPT 1-1/2˝ male NPT 3/4˝ BSPT 1˝ BSPT 1-1/2˝ BSPT 1-1/2˝ sanitary clamp 2˝ sanitary clamp

(Minimum length is 6˝, with 3/4˝ sensing tip)

M20 conduit connection

Window cap

Food grade wetted materials

Rod: 316 SS, .375˝ diameter, with 3/8-16 threaded tip

OPERATING PRINCIPLE Capacitance and Dielectrics

Capacitance is the property of two or more conductors to store a charge when there is a voltage difference between the conductors. In other words, capacitance relates the voltage between two conductors and the amount of charge that can be held on the conductors (i.e., the number of electrons). Capacitance is measured in Farads, but since a Farad of capacitance represents a very large charge storage capacity, most capacitance encountered is generally measured in micro Farads (µF, 10-6) or pico Farads (pF, 10-12). Capacitances encountered in level sensing applications are generally in the pico Farad range.

The material between the conductors also affects the capacitance. Insulating materials

do not allow free movement of electrons, however, in an electric eld the molecules of these materials will tend to align with the eld, thus storing energy. This is called

the dielectric effect and these materials are often referred to as dielectrics. When placed between two conductors the energy storage capability of these dielectrics will allow more charge to be stored on the conductors for a given voltage difference thus increasing the capacitance between the conductors. The ratio of capacitance change caused by these dielectrics is referred to as the dielectric constant. Different materials have differing dielectric constants and will consequently change the capacitance between two conductors more or less depending on the value of this constant. This value ranges from 1.0 for a vacuum to over 100 for certain materials. The dielectric constant for air is very close to 1.0 and usually assumed to be exactly 1.0.

Capacitive level sensors determine the level of material by changes in probe capacitance resulting from the movement of dielectric materials between the probe and the reference ground such as a tank wall. Since measuring very small capacitance changes (less than 1 pF) can be problematic in industrial environments, capacitance level sensing tends to be most effective for materials with a dielectric constant greater than about 1.2. Since the difference in capacitance is being measured, it is also possible to detect the level of two immiscible liquids that have different dielectric constants such as oil and water.

Level Detection

The CLS2 uses the capacitance difference between the uncovered sensor and covered sensor to sense level such as the probe in air verses the probe in oil. This would allow, for instance, detection when the level in a tank is below a threshold and a pump must be started or when the level is above a threshold where the pump must be turned off.

The CLS2 can be used in applications were the probe gets coated or covered with sticky, dusty, or clingy materials. The CLS2 has an active guard near the top that compensates for material that coats the probe preventing false alarms.

When detecting level, two critical items must be established: a reference capacitance and the sensitivity. The reference capacitance is set through an automatic calibration process. The sensitivity is selected using an internal DIP switch which provides 8 sensitivity levels to accommodate differing material dielectric constants. See the

calibration section for specic calibration instructions.

The level detection is available to external systems through a double pole double throw (2-form C) relay. In any alarm or control system some consideration must be made for a power failure in one or more elements of the system. The CLS2 provides a fail-safe selection that allows the relay to operate in either a normally open or a normally closed state when the probe is uncovered.

INSTALLATION Unpacking

Remove the CLS2 from the shipping carton and inspect for damage. If damage is found, notify the carrier immediately.

Mounting Location

The CLS2 is designed to be mounted in a tank and is rated for industrial environments with few restrictions, however certain considerations must be made to ensure optimal sensing and extended operational life.

• The process temperature and ambient temperature must be within the specied

limits for the instrument.

• Avoid locating the unit near or in high mechanical shock or vibration areas.

• The probe must be located away from tank inlets or chutes where material may fall

on the probe during lling or emptying.

• Avoid mounting the probe close to tank structures as conductive product bridging between the guard and tank structure can cause false alarms.

• In nonmetallic tanks a ground reference must generally be provided. If the probe is near the wall of the tank an adhesive backed metallic sheet may be applied to

the outside of the tank wall nearest to the probe. Other metallic objects may be

used also if they are in close proximity to the tank wall. If the probe is located further than 10 inches from the wall, an internal conductor must be provided parallel to and within 10 inches of the probe. These conductors must be connected to the case ground of the sensor. An external ground clamp is provided for this if other grounding is not available.

Wiring

WARNING

CAUTION

Torque terminals to 5 in-lb. Strip the wires 0.25˝.

Note: Installation must be made in accordance with National Electric Code and local

codes and regulations. When shing wire through the conduit connection do not allow

the wire to touch or press on components on the boards. Damage to the circuitry may result.

The unit is to be wired to a switch or circuit breaker in close proximity to the unit. The switch or circuit breaker shall be marked as the disconnections device for the unit.

The CLS2 has a 1/2˝ female NPT conduit connection. The conduit connection must be

made such that condensation is not allowed to enter the housing.

Grounding: The case of the CLS2 must be wired to a protective earth ground. This may be done by using a metal conduit or by wiring to one of the protective earth ground screws in Figure 1 or Figure 2.

The terminal block may be removed for easier connection. To remove, place a small screwdriver between the terminal block and the connector base and pry the terminal block forward. This will unlatch the block from the base allowing it to be removed. When installing the block, tip it forward on the connector base to snap it in the forward locking tab then rock the connector back onto the contacts until it snaps in place. Make sure the terminal block is securely in place.

Always install or service this device with the power off and where required install a disconnect lockout.

For power line connections use NEC Class 1 wiring rated 75°C. Use 12 to 20 AWG copper only for line and load connections.

Protective

earth

ground screw

Controls and Indicators (See Figure 2 and 3) Calibrate Switch—Pressing this switch twice initiates the automatic calibration

process. Time Delay Potentiometer—This control selects a delay time from 0 to 60 seconds from the detection of a level change to the output.

Dip Switch—This four section switch selects the sensitivity level and failsafe mode. Sensor LED—Yellow. This LED is illuminated immediately when the probe capacitance

exceeds the setpoint threshold. Output LED—Red. This LED is illuminated when the relay is powered. It is affected by the failsafe setting and the delay. Power LED—Green. This LED is illuminated when the unit is powered and indicates that power is being supplied to the sensing circuitry. External LED—Red. The external LED indicator operates in conjunction with the

internal Output LED.

External Calibration Magnet—An external magnet is provided on the end of a chain to initiate calibration without having to open the case. Calibration is started by touching the magnet to the label target twice.

Calibrate

switch

Output LED

(RED)

Figure 1: Terminals

Time delay

potentiometer

NONO

Sensitivity

Failsafe

External

LED

Strip 0.25˝ of insulation from the wires. Connect the power wires to terminals 1 and

2. If powered by DC, the polarity is not critical and either terminal may be selected for positive or negative. Connect control lines to the relay contact terminals (see Figure 1 for terminals). Torque terminals to 5 in-lb.

External

calibration

magnet

Sensor LED

(YELLOW)

Power LED

(GREEN)

Protective

earth

ground screw

Figure 2: Swiches and LED’s

4. Time Delay Selection: The time delay is the programmed time between when the probe senses the material and when the relay changes state from the sensed material. A time delay of 3 seconds or greater is required to meet CE requirements.

Choose a delay setting appropriate for the specic application. Adjust the delay

potentiometer to the desired delay (see Figure 2). The delay can be set anywhere

from 0 to 60 seconds and a scale is printed on the sensor board. For verication of

delay programming the yellow sensor LED will come on when material is sensed and the red output LED will come on with the relay after the programmed time delay.

5. Verify Operation: Make sure the probe is uncovered, material at least 5 inches

below the probe, and that the yellow sensor LED is off. Fill the tank until the material is at the desired threshold level and verify that the sensor LED is illuminated. If the sensor LED turns on before the material reaches the probe, reduce the sensitivity as needed. If when the probe is covered the sensor LED is not illuminated, increase the sensitivity. Water or other conductive liquids will activate the sensor when they just contact the probe. Low density and dielectric constant material may require more of the probe to be covered.

Figure 3: Magnent location

Setup and Calibration

1. Fail Safe Mode Selection: The relay will always be off when the power fails. In this

case the contacts identied as normally open will be open. The fail safe switch

selects whether the normally open contacts are open or closed when the probe is uncovered. There are two options for the failsafe condition that are selected by DIP

switch S4 (see Figure 2). Selecting normally open (NO) will force the relay contacts

to be open when the probe is uncovered and the output status LED to be off. Selecting normally closed (NC) will energize the relay when the probe is uncovered and light the output status LED.

2. Sensitivity Selection: The sensitivity must be selected to match the dielectric constant of the material and its density. Eight sensitivity levels are provided by positioning DIP switches S1, S2, and S3 (see Figure 2). A high sensitivity setting is a low pF, and a low sensitivity setting would be a high pF. High sensitivity is used for materials such as plastic pellets, light powders, and dry grain. Medium

sensitivity is used for materials such as cement, petroleum products, and our.

Low sensitivity is used for products such as aqueous solutions. The switch positions are summarized in Table 1. For best operation use the minimal sensitivity required for reliable operation.

Switch 1 Switch 2 Switch 3 Sensitivity

On Off On Off On Off On Off

On On Off Off On On Off Off

Table 1: Switch position for sensitivity

On On On On Off Off Off Off

1 pF 2 pF 4 pF 6 pF 8 pF 10 pF 14 pF 20 pF

Note: Default values as the product ships from the factory is a follows: S1:off, S2:off, S3:on, S4:on, and time delay off.

MAINTENANCE

Other than the controls mentioned in this manual there are no user maintenance

adjustments or routine servicing required for this product. Very heavy buildup on the probe may ultimately reduce sensitivity. Moderate buildup is compensated for by the active guard.

The Series CLS2 Capacitive Level Switch is not eld serviceable and should be returned if repair is needed (eld repair should not be attempted and may void warranty). Be sure to include a brief description of the problem plus any relevant

application notes. Contact customer service to receive a return goods authorization (RGA) number before shipping.

When the CLS2 with a Sanitary Process Connection is to be used in a sanitary or hygienic application, the unit must be cleaned and/or sanitized in accordance with appropriate guidelines prior to installation. The CLS2 with a Sanitary Process Connection is suitable for “Clean In Place” methods.

Explanation of Symbols:

Symbol Description

Earth (ground) terminal

Both direct and alternating current

Caution, risk of danger

3. Calibration: Calibrate with the probe uncovered and the material at least 5 inches below the probe. To start the automatic calibration process press the calibrate switch twice (see Figure 2) or press the external magnet up to the housing at the marked location on the housing twice (see Figure 3). The external magnet is attached to the housing by a chain. The output status LEDs will begin to blink slowly, about once per second, when the calibration process has started. The automatic calibration will

take approximately 10 to 15 seconds, and the output status LEDs will stop ashing

at the end of the calibration process. If during the calibration process the tank level changes or a sensor failure has occurred, the calibration process may fail. The

output status LEDs will begin to ash rapidly (about 4 times per second). Make

sure the probe is uncovered and retry the calibration step.