CLW Series Miniature capacitive point liquid level sensors FEATURES · Contact-free measurement of point liquid level · Measurement of both metallic and non-metallic substances · Measurement of granular or pulverised materials · Positioning/proximity sensor · Displacement sensor · Easy mounting · RoHS compliant · Quality Management System according to ISO 13485:2003 and ISO 9001:2008 ELECTRICAL CONNECTION SPECIFICATIONS Maximum ratings Supply voltage (VS) Output voltage (Ri=1 kΩ) Operating temperature range 5.5...15 VDC 5V -20 ... 85 °C VS NC Switch Teach-in GND E / 11664 / H 1/6 www.first-sensor.com www.sensortechnics.com CLW Series Miniature capacitive point liquid level sensors PERFORMANCE CHARACTERISTICS Characteristic Min. Measuring range (adjustable hysteresis)1 0.1 Response time 10 Typ. 50 Max. Unit <25 mm 1000 ms Note: 1. For a measuring range of <25 mm the sensor has to be mounted in vertical position (compare MOUNTING on page 3) OUTPUT SIGNAL As soon as the medium reaches the TIHIGH value, the sensor gives a logic ‘HIGH’ (5 V). Per factory default or the medium below the TILOW value, the sensor gives a logic ‘LOW’ (0 V). The range between TIHIGH and TILOW is the sensors' hysteresis. ELECTRICAL CHARACTERISTICS Pin Pin name 1 V S4 Explanation Supply pin2 Current draw of sensor 2 NC Switch 4 TI Output voltage (Ri=1 kΩ) Teach-in3 Current draw GND Typ. Max. Unit 5.5 9 15 V 7 8.5 10 mA 0 5 V -0.25 5.25 V 1 mA not connected 5 3 5 Min. Ground Note: 2. Length of power supply cable must not exceed 2.5 m. 3. Only for Teach-In, do not connect during operation. (TIHIGH=4.5...5.25 V, TILOW=-0.25...0.5 V) 4. The quality of the supply voltage (with regards to ripple or other disturbances) may have an impact on the accuracy of the measurement. 5. No protection against electrical surge (e.g. with inductive load) ELECTRICAL CONNECTION (cont.) Pin 1 E / 11664 / H 2/6 www.first-sensor.com www.sensortechnics.com CLW Series Miniature capacitive point liquid level sensors MECHANICAL CHARACTERISTICS Wall thickness (glass) without air gap max. 7 mm Wall thickness (unfoamed plastic) without air gap max. 7 mm Connection output 5 pin JST connector (VS, Switch out, Teach-in, GND and Pin 2 (not connected)) Mechanical fixation Double-sided adhesive tape MOUNTING · The optimal distance between sensor and medium is <4 mm. · The maximum distance between sensor and medium is 7 mm of which 80 % must be of plastic or glass (less than 20 % air gap). · The sensor must be fixed on a surface free of grease or bubbles. Note: Please be aware that the sensor needs to be taught in the application with its specific mounting and environmental conditions. Any change in those conditions may result in erroneous measurements. Environmental conditions are defined by the presence, absence or position of objects in the vicinity of the sensor and/ or changes of electrical potentials. Vertical mounting position Advantage: Larger teachable measuring range Teachable measurement range CLW sensor Container wall E / 11664 / H Horizontal mounting position Advantage: Higher accuracy of switch point Teachable measurement range CLW sensor Container wall 3/6 www.first-sensor.com www.sensortechnics.com CLW Series Miniature capacitive point liquid level sensors GROUND REFERENCE The CLW sensor needs a proper ground reference (GND) to achieve optimum results. Toroidal transformer If a toroidal transformer is used as a power supply, the capacitive coupling between primary and secondary coil is sufficient to ensure proper grounding. Switched power supply In case a switched power supply is used (which is usually floating), the ground reference could be oscillating by as much as 50 % of the mains voltage, potentially resulting in erroneous measurements. Solutions: Non-floating ground reference To ensure non-floating of the ground reference, the sensor's GND pin has to be connected to earth potential (PE). However, this setup could result in a leakage current causing the residual current circuit breaker to switch. Further, a galvanic connection does exist between the sensor and PE. Power supply + +Vs - GND CLW PE Virtual ground reference A capacitor between the sensor's GND pin and earth potential (PE) will solve the problem of leakage current and should be used in most cases. In this setup a galvanic isolation is established between the sensor and PE. Power supply + +Vs CLW - GND 0.1 µF PE E / 11664 / H 4/6 www.first-sensor.com www.sensortechnics.com CLW Series Miniature capacitive point liquid level sensors TEACH-IN The Teach-In (TI) mode allows for a permanent storage (EEPROM) of both low and high level switch points. The TILOW mode stores the value for the low switch point and adapts to the corresponding application conditions. The TIHIGH mode stores the value for the high switch point with the container filled to the desired level. By factory default the sensor is ‘formatted’ and needs to be taught to provide an output signal. By teaching the sensor, a hysteresis can be generated which suits the requirements of the specific application (i.e. operation of a pump which shall be switched on at the LOW TI-point and switched off at the HIGH TI-point). Example: Teach-In HIGH (sensor switches on) Teach-In LOW (sensor switches off) Sensor hysteresis Teachable measurement range CLW sensor (in vertical mounting position) Container wall Preconditions for successful Teach-In · · · · · · Do not touch the sensor or container during the Teach-In or measuring process. The sensor must be in original mounting position. After connecting to VS the sensor must level off for 2 sec. Important: The sensor must first be taught LOW to adapt to the ambient conditions, then HIGH. The TIHIGH value must not be lower than the TILOW value. Best results will be achieved when GND is connected to earth potential (see GROUND REFERENCE). Note: The maximum tolerable voltage range for the TI pin is -0.25…+5.25 V. TILOW mode: Apply voltage between 0 and 0.5 V for at least 500 ms at the Teach-In pin. After 1 sec. the value is stored in the EEPROM. TIHIGH mode: Apply voltage between 4.5 and 5 V for at least 500 ms at the Teach-In pin. After 1 sec. the value is stored in the EEPROM. Under normal conditions, the TI-Pin delivers 2.5 V. It is possible to re-teach the HIGH level only (in case, the LOW level remains the same). A re-teaching is only possible after having disconnected the supply voltage. However, if the LOW level needs to be changed, the sensor first has to be formatted (see Reset). Reset The sensor can be reset to factory default (’format’) as follows: 1. Disconnect the sensor from VS . 2. Connect the TI-Pin (pin 4) to GND. 3. Connect the sensor to VS for at least 2 sec. 4. Disconnect the sensor from VS and formatting is completed. E / 11664 / H 5/6 www.first-sensor.com www.sensortechnics.com CLW Series Miniature capacitive point liquid level sensors OUTLINE DRAWING 28.5 ±0.3 Label 25 ±0.3 Note: The max. sensor height incl. connector is 8 mm. Connector dimensions in mm ORDERING INFORMATION Series Options CLW Measuring range* 025 <25 mm * Adjustable hysteresis Example: CLW 025 Output F* Supply 5V 15 5.5...15 V Housing N No housing * Ri=1 kΩ F 15 N Note: Custom specific options are available. Please contact First Sensor for further information. Accessory (Not included in delivery! Please order separately.) Order No. Description ZK000133 JST connector/cable assembly (approx. 29 cm cable length) First Sensor reserves the right to make changes to any products herein. First Sensor does not assume any liability arising out of the application or use of any product or circuit described herein, neither does it convey any license under its patent rights nor the rights of others. E / 11664 / H 6/6 www.first-sensor.com www.sensortechnics.com