Operation; Measurement; Low Power Operation; Long Cable Lengths - Campbell EE181 Instruction Manual

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Operation

8.1

Measurement

8.2

Low Power Operation

8.3

Long Cable Lengths

Model EE181 Temperature and Relative Humidity Probe
FIGURE 7-2. EE181 and RAD10E Solar Radiation Shield on a tripod
mast
The probe uses E+E Elektronik's coated HC101 capacitive sensor to measure
RH and a 1000 Ω PRT to measure temperature. Campbell Scientific
dataloggers measure the analog voltage outputs of the EE181 Temperature and
Relative Humidity Probe with the VoltSE() measurement instruction.
The EE181 draws less than 1.2 mA powered from 12 V. The EE181 can be
continuously powered from the 12V terminal, or power can be switched with
the SW12V terminal to conserve battery life. When power is switched, a two-
second warm-up period is required. This is programmed with the Delay()
instruction, using 0 for the delay option.
Long lead lengths cause errors in the measured temperature and relative
humidity. The approximate error in temperature and relative humidity is
0.31 °C and 0.31% per 100 feet of cable length, respectively.
When long lead lengths are required and the above errors in temperature and
relative humidity are unacceptable, use the HC2S3 or HMP155A temperature
and relative humidity probe.
Understanding the following details are not required for the general operation
of the EE181 with Campbell Scientific's dataloggers. The signal reference and
the power ground (black) are the same lead in the EE181. When the EE181
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