Apogee S2-122 소유자 매뉴얼 - 페이지 14

{카테고리_이름} Apogee S2-122에 대한 소유자 매뉴얼을 온라인으로 검색하거나 PDF를 다운로드하세요. Apogee S2-122 16 페이지. Pri sensors

TROUBLESHOOTING AND CUSTOMER SUPPORT

Independent Verification of Functionality

Apogee S2 series PRI sensors are self-powered devices and output a voltage signal proportional to irradiance

(upward-looking sensors) and radiance (downward-looking sensors). A quick and easy check of sensor functionality

can be determined using a voltmeter with millivolt resolution. Connect the positive lead wire from the voltmeter

to the yellow wire from the sensor and the negative (or common) lead wire from the voltmeter to the blue wire

from the sensor. Direct the sensor head toward a light source and verify the sensor provides a signal. Increase and

decrease the distance from the sensor head to the light source to verify that the signal changes proportionally

(decreasing signal with increasing distance and increasing signal with decreasing distance). Blocking all radiation

from the sensor should force the sensor signal to zero. Repeat the process by connecting the positive lead wire

from the voltmeter to the white wire from the sensor and the negative (or common) lead wire from the voltmeter

to the black wire from the sensor.

Compatible Measurement Devices (Dataloggers/Controllers/Meters)

S2-100 series PRI sensors have small sensitivities, outputting a few mV per W m⁻². Typical irradiance from the sun

-2

on a clear day is between 1-2 W m

at the center wavelengths measured by the sensors. It is recommended that

the measurement device (e.g., datalogger or controller) have resolution of at least 0.001 mV.

Example datalogger programs for Campbell Scientific dataloggers can be found on the Apogee webpage at:

https://www.apogeeinstruments.com/content/PRI-Analog.CR1

Cable Length

When the sensor is connected to a measurement device with high input impedance, sensor output signals are not

changed by shortening the cable or splicing on additional cable in the field. Tests have shown that if the input

impedance of the measurements device is greater than 1 mega-ohm there is negligible effect on the calibration,

even after adding up to 100 m of cable. All Apogee sensors use shielded, twisted pair cable to minimize

electromagnetic interference. For best measurements, the shield wire must be connected to an earth ground. This

is particularly important when using the sensor with long lead lengths in electromagnetically noisy environments.

Modifying Cable Length

See Apogee webpage for details on how to extend sensor cable length:

(http://www.apogeeinstruments.com/how-to-make-a-weatherproof-cable-splice/).