Apogee TS-100 Benutzerhandbuch - Seite 17

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compatible measurement device should have resolution of at least 0.008 mV, in order to produce
temperature resolution of less than 0.1 C across the entire temperature measurement range.
To operate the fan, a 12 V DC power supply capable of supplying at least 80 mA is required. All fans also
include pulse width modulation (PWM; allows for reduction of fan speed under certain conditions) and a
tachometer (allows for monitoring of fan speed). In order to use the PWM option, the fan must be
connected to a datalogger or controller that has a PWM output of approximately 20 kHz, a duty cycle of
50 to 100 %, and a 0 to 5 V DC square waveform. To measure the output from the tachometer, a pulse
counter is required. The maximum voltage input from the tachometer to the pulse counter is determined
by the input voltage to the tachometer, which should be fixed at a given voltage in the range of 0 to 30 V
DC. The measurement device should be capable of supplying a fixed voltage in this range.
An example datalogger program for Campbell Scientific dataloggers can be found on the Apogee
webpage at http://www.apogeeinstruments.com/content/Aspirated_Shield.CR1.
Effect of Cable Length:
When the temperature 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 1 mega-ohm or higher then there
is negligible effect on the sensors, even after adding up to 100 m of cable. TS-100 aspirated radiation
shields use shielded, twisted pair cable, which minimizes electromagnetic interference. This is particularly
important for 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/).