LT-2M LEAF TEMPERATURE SENSOR

Transcription

1 USER MANUAL INSTALLATION AND OPERATION LT-2M LEAF TEMPERATURE SENSOR PHYTOMONITOR SERIES

2 SECTION 1 - GENERAL INFORMATION Description The LT-2M sensor is designed for monitoring absolute temperature of leaves. It is a two-channel transducer, equipped with the two temperature sensors. The LT-2M sensor includes two semiconductor bead thermistor provided with the special clips for attaching it directly to the leaf under study (See Fig 1). A signal conditioner converts the resistance of the thermistor to output voltage. The LT-2M sensor requires an external regulated power supply and a datalogger (recorder) for operation. To provide the best achievable resolution and accuracy, the datalogger s input has to be equipped with a filter with a cutoff frequency below 10 khz. Operating Precaution 1. The LT-2M sensor is a fragile instrument. Its components are sensitive to external force and shock. Do inspect the sensor regularly. 2. Turn off the power whenever you connect a sensor to power supply or datalogger. Fig. 1. General design of the LT-2M sensor. Page 2

3 SECTION 2 - SPECIFICATION Range of Measurement: 5-50 C (typical) Output: Non-linear over 0 to 2 Vdc 4-20 ma or 0-20 ma (optional) Interchangeability: Individual calibration is provided Instrumental Accuracy: ± 0.2 C Stability: ± 0.5 C over 1 year period Leaf-Air Temperature Deference Effect: less than +10% (Tl-Ta), where Tl-leaf temperature, Ta - air temperature Thermistor-leaf Contact Area: < 1 mm 2 Distance between Measured Spot and the Leaf Edge: 12 mm max. Overall Dimensions: 35 x15 x15 mm 3 Power requirements: 10 to ma max. Corrosion resistance All external parts are manufactured using stainless steel, Titanium and engineering polymers Lengths of the leads between 1 m typical a sensor and a signal conditioner SECTION 3 - INSTALLATION Connecting signal conditioner Connect a cable to an appropriate power supply and a datalogger (recorder) as it is shown in the connection diagram attached to every signal conditioner. Page 3

4 Installing Sensor 1. Switch power on. 2. Attach the sensor to a leaf as shown on the photo below. Thermistor should be placed at the lower shady side of a leaf. 3. Secure the sensor s cable on a stem to prevent occasional movement of the sensor. 4. Enter enclosed calibration data into the datalogger s memory according to hook-up instruction 5. Check the position of the sensor routinely. SECTION 4 - SERVICE AND MAINTENANCE The sensor must be kept reasonably clean to maintain measurement accuracy. Use a soft brush to clean the sensor. All the sensors are delivered properly calibrated. Contact your supplier to make on-demand calibration. SECTION 5 APPLICATION NOTES There are two basic requirements when conducting measurements of the leaf temperature: Minimal effect on the leaf temperature Maximal thermal contact between leaf and sensor. Page 4

5 The LT-2 sensor s design generally meets both requirements. A miniature bead thermistor has extre mely fine glassy cover. It is also spring-loaded that provides firm but gentle contact to the leaf surface. The thermal conductance of thermistor body is small but not negligible. Because of this conductivity, the difference between leaf and air temperatures may cause a systematic deviation, which has been estimated as 10% of the leaf-air temperature difference. Usually, the leaf-air temperature difference does not exceed ± 5 C and, therefore, the appropriate maximal deviation may be estimated as ±0.5 C respectively. If the leaf-air temperature difference is known, the correction can be applied to the result of measurement. SECTION 6 TROUBLESHOOTING Use the troubleshooting section in the datalogger instruction manual to determine whether the sensor or datalogger is defective. If the datalogger is not defective, check the connections and, if they are correct, refer to the warranty/replacement plan of your supplier. Should service, parts or assistance in troubleshooting or repair be required, please contact your supplier. A description of the malfunction as well as the proper return address should accompany all sensors returned for repair or recalibration. All sensors out of warranty should be accompanied by a purchase order to cover costs of repair. WARRANTY Any sensor which fails within 1 year from the date of shipment will be replaced free of charge (excluding failure due to physical breakage or damage resulting from excessive temperature or chemicals). The manufacturer shall not be liable for any consequential damages, whether to person or property, caused by a defective sensor Page 5