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OWNER'S MANUAL

TEMPERATURE SENSORS
Models ST-100, ST-110, ST- 150, ST-200, and ST-300
Rev: 14-Apr-2021
APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2021 Apogee Instruments, Inc.

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Summary of Contents for Apogee Instruments ST-100

  • Page 1: Owner's Manual

    TEMPERATURE SENSORS Models ST-100, ST-110, ST- 150, ST-200, and ST-300 Rev: 14-Apr-2021 APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM Copyright © 2021 Apogee Instruments, Inc.
  • Page 2: Table Of Contents

    TABLE OF CONTENTS Owner’s Manual ....................................1 Table of Contents ....................................2 Certificate of Compliance ................................. 3 Introduction ..................................... 4 Sensor Models ..................................5 Specifications ................................... 6 Deployment and Installation ..............................8 Operation and Measurement ..............................9 Maintenance and Recalibration ............................. 14 Troubleshooting and Customer Support ..........................
  • Page 3: Certificate Of Compliance

    RoHS 3 compliant using exemption 6c. Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end products for the presence of these substances, but rely on the information provided to us by our material suppliers.
  • Page 4: Introduction

    ST-110 sensors are weatherproof, have excellent long-term stability, but do not offer the same level of ingress protection as the ST-100. The ST-110 is designed for continuous air temperature measurement when housed in the TS-100 aspirated radiation shield. Thermal conductivity to the precision thermistor is minimized by using constantan wire, which has twenty-fold lower thermal conductivity than copper wire.
  • Page 5: Sensor Models

    SENSOR MODELS The ST-100 temperature sensor includes a rugged, weatherproof housing and can be exposed to a wide range of environmental conditions, including submersion in water and burial in soil/porous media. The ST-200 temperature sensor does not include the weatherproof housing and is designed for fast response measurements, or measurements of small samples and fragile surfaces.
  • Page 6: Specifications

    SPECIFICATIONS ST-100 ST-110 ST-200 ST-150 ST-300 Measurement Range -60 to 80 C 0.1 C (from 0 to 0.3 C (from -50 0.1 C (from -60 to 70 C), 0.2 C (from 0.1 C (from 0 to 0.2 C (from 0 to...
  • Page 7 Calibration Traceability Apogee ST-100, ST-110, and ST-200 temperature sensors are not factory calibrated but come with a generic calibration (see Steinhart-Hart coefficients in OPERATION AND MEASUREMENT section). A custom calibration can be derived by comparing the temperature from the thermistor to a reference temperature measurement. Often, a simple offset can be used to make measured temperature match reference temperature.
  • Page 8: Deployment And Installation

    When the condensed water evaporates, it cools the sensor via removal of latent heat (evaporational cooling). During installation of ST-100, ST-150, and ST-300 sensors in soil, care should be taken to minimize soil disturbance, which may potentially alter soil thermal properties.
  • Page 9: Operation And Measurement

    Wiring for ST-100 Serial Numbers 2725 and above, ST-110 Serial Numbers 2725 and above, and ST-200 Serial Numbers 1352 and above White: Single-ended channel (positive thermistor lead)
  • Page 10 Measurement devices (e.g., datalogger, controller) do not measure resistance directly, but determine resistance from a half-bridge measurement, where an excitation voltage is input across the thermistor and an output voltage is measured across the bridge resistor. NOTE: The wiring diagram above is based off the new wiring colors for serial numbers 2725 or 1352 and above.
  • Page 11 ST-150 The ST-150 does not include bridge resistors and therefore requires measurement with dataloggers or controllers that are capable of current excitation. Although the ST-150 can be used in a 2-wire or 3-wire measurement configuration, a 4-wire configuration is recommended for highest accuracy (4-wire measurement configuration eliminates the influence of lead wires).
  • Page 12 ST-300 PRT Connect the sensor to a measurement device (meter, datalogger, controller) capable of inputting 2.1 V DC, and measuring and displaying or recording a millivolt (mV) signal (an input measurement range of 16 to 27 mV is required to cover the entire temperature range of the sensor). In order to maximize measurement resolution and signal-to-noise ratio, the input range of the measurement device should closely match the output range of the thermistor.
  • Page 13 Measurement of PRT resistance is very similar to measurement of thermistor resistance, where a half-bridge measurement is used. An excitation voltage is input across the bridge resistor and an output voltage is measured across the PRT. NOTE: The wiring diagram below is based off the new wiring colors for serial numbers 1076 and above.
  • Page 14: Maintenance And Recalibration

    ST series temperature sensors used to measure air temperature should be periodically cleaned to remove all dust and debris. Apogee ST-100 temperature sensors are weatherproof and can be submerged in water or buried in soil/porous media. ST-110 sensors are weatherproof and designed for air temperature measurements inside radiation shields.
  • Page 15: Troubleshooting And Customer Support

    TROUBLESHOOTING AND CUSTOMER SUPPORT Independent Verification of Functionality Apogee ST Series thermistor temperature sensors yield a resistance proportional to temperature. A quick and easy check of thermistor/sensor functionality can be accomplished with an ohmmeter. Connect the lead wires of the ohmmeter to the red and white wires from the sensor.
  • Page 16 Modifying Cable Length When the sensor is connected to a measurement device with high input impedance, sensor output signals are not changed by splicing on additional cable in the field. Tests have shown that if the input impedance of the measurements device is 1 mega-ohm or higher then there is negligible effect on ST series temperature sensors, even after adding up to 100 m of cable.
  • Page 17: Return And Warranty Policy

    RETURN AND WARRANTY POLICY RETURN POLICY Apogee Instruments will accept returns within 30 days of purchase as long as the product is in new condition (to be determined by Apogee). Returns are subject to a 10 % restocking fee. WARRANTY POLICY...
  • Page 18 84321, USA 5. Upon receipt, Apogee Instruments will determine the cause of failure. If the product is found to be defective in terms of operation to the published specifications due to a failure of product materials or craftsmanship, Apogee Instruments will repair or replace the items free of charge.

This manual is also suitable for:

St-110St-150St-200St-300

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